There are several reasons why the correct answer is C.Prefixes always go at the beginning of a word. (option A and D are the last letters of the word)"EXCL" is not an existing prefix. The prefix "ex-" , in this case, means "out". This meaning is connected with the word "excluded". Bear in mind that prefixes change the meaning of words, for example: -
EXclude = to keep someone out of a place, group or situation.
INclude = to add something in, to make someone part of something.
In this example you have the same word ending, what changes is the prefix and that's what determines the meaning of the word.
The prefixes are a group of letters or one single letter placed and attached before the root word, and at the same time provides meaning to the complete word. For example "impossible" in this case the prefix would be "im".
Hence, the correct answer is letter c. ex
the prefix in the italicized word in the sentence above is