Use whatever you want unless your homework (and this is clearly homework) requires a specific control structure. There's not a single way to accomplish most programming problems, so you need to figure out which ones will work and choose between them.
As a beginner in C, you DEFINITELY want to use an array of chars for the words:
Where NumberOfWords could be just a few hundred or 40,000 or more. There are very few English words that are longer than 39 letters, (save 1 space for the end of string char), outside of scientific nomenclature.
You'll want to declare this array above main(), to get global memory (heap), not try to use the smaller stack inside a function, for it.
Word lists are available on the net, btw. A single word can then be referenced with
words, in a loop, like:
while((fscanf(YourFilePointer, "%s", words[i]))>0)