The Philadelphia chromosome, which is an abnormality in chromosome 22, is most often found in bone marrow cells of patients with chronic myelogenous leukemia. It may also occasionally be found in acute lymphocytic leukemia, though this is rare.

Reed-Sternberg cells are the pathognomonic cells of Hodgkin's lymphoma. These are mutated multinucleated B cells with a large amount of cytoplasm. These cells can be present in other pathologies - the diagnosis of Hodgkin's lymphoma can only be made if the Reed-Sternberg cells are in the presence of non-neoplastic inflammatory cells such as lymphocytes, plasma cells, and eosinophils.

Bence-Jones proteins are present in the urine of over 60% of multiple myeloma patients.Albumin may be present in the urine of these patients, but it is not pathognomonic for multiple myeloma. Alpha-synuclein is associated with neurodegenerative conditions, and tau 64 is a protein present in the neurons of patients with Alzheimer's disease.

The most common symptom of Hodgkin's lymphoma is the painless enlargement of one or more lymph nodes. 

Unexplained weight loss and fatigue may also be present, but are more likely to present later than lymph node enlargement. Bone pain and easy bruising are not typically seen.

In prostate cancer, patients will have elevated levels of prostate specific antigen (PSA). Cancer antigen 125 (CA 125) is elevated in ovarian cancer, alpha-fetoprotein (AFP) is elevated in hepatocellular carcinoma, and tyrosinase is an enzyme that is often highly elevated in malignant melanoma.

Leukemia is a cancer of white blood cells, limiting the ability of the body to fight infection. Patients with leukemia exhibit altered leukocyte counts (less than ), as well as ulcerations of the mouth and throat, pneumonia, septicemia, anemia, fatigue, lethargy, weakness, pallor, weight loss, headache, disorientation, and forms of bleeding, including bleeding gums, ecchymosis, petechiae, and retinal hemorrhaging. Patients with leukemia do not usually exhibit weight gain (usually loss), high red blood cell counts (usually anemic), and flushing (usually pallor).

All of these may be factors in the diagnosis of cancer. The operative word in the question is ‘risk.’ Common risk factors for breast cancer include previous immunosuppression, advancing age, and genetic predisposition. Common causative factors include smoking, alcohol use, radiation,  chronic irritation, consumption of food additives, exposure to industrial chemicals such as asbestos, exposure to dangerous pharmaceuticals such as stillbesterol, previous viral infection such as Epstein-Barr, and stress (when combined with other causative factors).

The correct answer is "Cancer antigen (CA-125)" because CA-125, also known as mucin 16, is a glycoprotein that is found to have elevated serum levels in patients with a variety of cancers (including ovarian cancer) and benign conditions, as compared to patients without such conditions. As a result, monitoring CA-125 levels can be used as a method of tracking disease progression or response to treatment based upon what the initial CA-125 level is at the time of diagnosis. 

On the other hand, the other choices are incorrect. Cancer antigen 19-9 (CA 19-9) is incorrect as this is a biomarker in pancreatic cancer, not ovarian cancer.Prostate specific antigen (PSA) is incorrect as this is a biomarker in prostate cancer (and other prostate conditions), not ovarian cancer. c-KIT is incorrect as this is a biomarker in gastrointestinal stromal tumors, not ovarian cancer. BCR/ABL is incorrect as this is the translocation found in the Philadelphia Chromosome implicated in chronic myelogenous leukemia, not ovarian cancer.

The correct answer is "Cancer antigen 19-9 (CA 19-9)" because CA 19-9 is often elevated in patients who have pancreatic cancer (or certain types of colon cancers), and can be used to assess response to treatment and/or disease progression. 

On the other hand, the other choices are incorrect. Cancer antigen-125 (CA-125) is incorrect as this is a tumor marker used to track ovarian cancer, not pancreatic cancer. CD20 antigen is a tumor marker for B-cell lymphomas and leukemias, not pancreatic cancer. CD30 antigen is a tumor marker for anaplastic large cell lymphoma, not pancreatic cancer. BRAF is a tumor marker for melanoma, not pancreatic cancer.

A CT scan is the preferred imaging modality to view a tumor in the lung tissue. A chest x-ray might initially find a nodule or abnormal marking in the lungs, but it must be followed up with a CT scan to be diagnostic. EKG looks at the heart and EEG looks at the brain.