The sentence actually has no verb as written, as the word that is trying to function as a verb, "willing," is a participle that cannot stand alone as a verb. Instead, it needs a form of the verb "to be" attached to it to fully function as the verb in the sentence. Therefore, the correct answer choice is "usually requires the employee to be willing to take," as it is the only one that employs such a usage.

The underlined portion of the sentence is one part of a compound sentence, and can therefore function as a complete sentence structurally. However, the participle "keeping" cannot stand alone as a verb, and the proper verb needs to match the past tense "picked" in the second clause of the sentence. "Their mother kept her promises" is the only answer choice that features the correct verb form.

The use of the participle "growing" makes the sentence actually not have a verb, as a participle needs some form of the verb "to be" to make a complete verbal phrase. "Growing" needs to be changed to a verb that can work on its own as the main verb of the sentence. The only answer choice to do so is "the business grew rapidly."

The use of the participle "working" as the verb in the sentence is incorrect, as a participle needs some form of the verb "to be" with it to complete a full verbal phrase. The verb "working" needs to be changed to a proper verb form. The only answer choice that uses a correct verb form is "The team worked toward a common goal."

The use of the participle "keeping" as the verb in the sentence means the sentence actually does not have a verb, as a participle needs a version of the verb "to be" to make a usable verbal phrase. The only answer choice that appropriately takes care of this problem by changing the verb form is "The old woman kept pets in unsafe conditions."

The use of the participle "keeping" makes the sentence have no actual verb, as a participle needs some form of the verb "to be" in order to stand as the main verb of a sentence. The verb form should be changed to one that can actually function as a verb in the sentence. "The reclusive man never kept up with any of his old friends," which uses the past tense verb "kept," is the only answer choice that uses a correct verb form.

"Seeing" is an incorrect verb form, as it is a present participle, used with a past tense verb, "had." The verb form needs to be changed to make it the past participle form. The only answer choice that uses the correct verb form is "had never seen a building."

The use of the present participle "showing" as the verb in the sentence makes the verb actually not have a verb. A participle needs to be accompanied by some form of the verb "to be" in order to be a workable verb in a sentence. The answer choice that corrects this issue is "showed great aptitude for playing the piano," which uses a straightforward past tense verb.

The use of the participle form "making" is awkward in this sentence, as a participle can only be used with a form of the verb "to be." The word can be changed to an infinitive form, making it pair better with a regular past tense verb to show what the man was working towards. Therefore, the correct answer is "The old man worked to make sure that he could get home before the sunset."

The use of the present participle "having" as the main verb makes this sentence actually have no verb. A participle can only be a complete verb if it is used with some form of the verb "to be." "The novice had few role models in his career," using the simple past tense form, is the only answer choice that fixes this issue.