When something is "luxurious," it is expensive and often unnecessary. When we speak of "luxuries," we are often speaking of items that we do not need, though we want them. For example, a very expensive car is a luxury item. We buy it because it is magnificent and wonderful, not merely because it is something that we need. Hence, the word "luxurious" can mean "magnificent" because such luxurious things tend to be very grand.

The word "typical" is related to "type," meaning kind. For example, you could say, "It was the type of day that makes you very cold." This is the kind of day that makes you cold. When something is "typical" it is just as expected. Thus, a "typical winter day" is one that is just how you would expect it to be. It is average or ordinary.  Hence, "average" is the best option.

The word "satisfactory" comes from the Latin for enough. When we are "satisfied," we have had enough of something. When something is "satisfactory," it is good enough. Therefore, the best answer is "acceptable." Several of the options are too positive. You cannot say that something "satisfactory" is "excellent" or "superb."

The word "inferior" comes from roots that mean below or low. When something is of "inferior quality," it is of poor quality.  The only option that expresses this is "unsatisfactory," which indicates that something is not good enough.

In science, we use the word "universe" to describe everything that exits. When something is "universal," it is true everywhere. Therefore, you could say, "It is a universal opinion that everyone should brush his or her teeth at night." This means that everyone thinks this. When something is "universal" in this manner, it is common. A "common opinion" is one that is held by almost everyone.

When something is "plain" it is not very complex. We might also say that it has "no frills." "Ordinary" things are normal, not too different from whatever is "normal" or "regular." In this sense, we can say that "ordinary" can be a synonym for "plain." Thus, an "ordinary dress" is one that is likely "plain."

The word "foul" can have a number of different uses. It generally describes something that is very negative. Thus, a "foul mood" is a very bad mood. A "foul person" is someone who is very nasty. Something that is "foul" can also be something very rotten. Thus, "foul meat" is very rotten meat. From this, the word "foul" can also be used to describe the very strong odor or ugly appearance of the thing. Therefore, it can take on the meaning, "Disgusting." This is the sense in which it is being used here.  

Whenever someone prospers, he or she is doing well for himself or herself. Thus, a prosperous business owner is someone who has developed his or her business very extensively. Often, this means that the person who is prosperous has become wealthy.  None of these options deal with wealth directly. However, "thriving" is a good synonym for "prosperous." A "thriving" business is a "prosperous" business.

Do not be tempted by the fact that "forged" documents are often illegal. The act of "forgery" is the act of faking something, making it look as though it were official or true. For example, we can forge a signature, signing a document so that it looks like someone else actually signed it. This is a kind of "faking." Hence, the best option is "faked."

The word "incredible" is related to the Latin meaning I believe. Whenever we say that something or someone is "credible", we mean that it is believable. For example, in a court case, we can say that someone is a "credible witness." This means that he or she is the kind of witness that we should believe. When something is "incredible" it is unbelievable. Sometimes, we use this word to mean "remarkable". For example, we would say, "That was an incredible fireworks show!" This means that it was really stupendous. The word "incredible" can also mean unbelievable. That is the sense of "implausible." When something is "plausible" it is probable or at least possible. Something "implausible" is just totally unlikely to be true.