When you "fasten" two things together, you somehow tie or attach them together. When you "fasten your belt" in the car, you are connecting its parts together, "snapping them into place." Although many words could be used as synonyms for "fasten," the simple "attach" works best among the options provided. If you fasten something to the wall, you do, certainly, attach it to the wall.

The word "bleed" does of course have to do with blood and health often; however, it basically means "to flow." For example, people will "bleed" radiators to leave out extra air so that more water can enter them. The word "seep" expresses this kind of bleeding. Think of when you paint with water colors. They often can seep into each other. We almost naturally say, "The colors are bleeding into each other." This is the meaning we are looking for in this question!

When a body of water "overflows," it goes over the edges of its container. If you were to have the water overflow in your bathtub, it would spill out over the top of the tub. In order to "overflow" this kind of spilling is necessary - not just mere rising of water levels. Now, none of the options directly deals with this kind of spilling. However, the word "flood" does indicate what happens when some bodies of water overflow. Thus, since this is the only good option, you should choose it.

An "assembly" is a gathering of people. Do not let this lead you to think that "assemble" (or "assembly") only has to do with religious services. (We do use it in this sense regularly.) Several of the options try to make you choose options dealing with such particular kinds of assemblies. The general meaning of "assemble" is to gather together things into a group—whether you "assemble" people, toys, or other things. Thus, "collect" is the best option provided.

The word "emerge" means to come out. Perhaps you know the word "submerge," which means to go under. The prefix "sub-" means under, and the prefix "e-" means out of. (Sometimes, this prefix is "ex-".) Thus, we can say that "appear" is a synonym for "emerge." For example, you can say, "He emerged into sight after being in hiding." This means that the person appeared in sight.

You likely have seen an "escalator" in a store. These are moving stairs that go up and down mechanically. The word "escalate" means to increase or become more intense. Whenever we say, "The violence in the area escalated," we mean, It became more violent in that area. Thus, the only option that is a good synonym is "increase."

The word "diminish" comes from roots meaning to become smaller. You can see in it the "-min-" root that is used in words like "miniature" and "mini." Therefore, the only option that is correct is "lessen." Whenever we "lessen" the strength of something, we make it weaker. That is, we make it "smaller" in strength.

A "crease" is a fold in something. It can be in a piece of paper or in someone's clothes. The verb "to crease" merely indicates the action of making such a fold.  

The word "manufacture" actually comes from roots meaning to make with one's hands. Something is "manual" when it is able to be done or used with a hand. Even the little books that we call "manuals" are give this name because they are small enough to fit in a hand. The second half of the word means to do or make. This "-fact-" root is used in many words in English. Thus, the best option is "produce." A manufacturer is someone who produces a product. The verb "to manufacture" describes the process of making that product.

Whenever someone "deviates" from the norm, he or she departs from it. Deviations are a kind of straying from what is acceptable or expected. You can also simply "deviate from the path" when walking somewhere. This means that you stray from it. In general, you can use "deviate" and "stray" to express this idea of "going away from the expected procedure, norm, or path." Therefore, they are good synonyms.