In the following sentence, identify the part of speech of the italicized word.

Catching fish is one of the oldest pastimes.

the italicized word is is.

A. Adverb
B. Conjunction
C. Preposition
D. Verb

I thought it was a preposition at first but after some reading I know it cant be. now I think its a verb but I want to double check. can anybody confirm or deny for me?

Yes, it's the main verb of this sentence.

To determine the part of speech of the word "is" in the sentence "Catching fish is one of the oldest pastimes," you can consider the function it performs in the sentence.

In this case, "is" is the main verb of the sentence, which indicates the existence or state of being. It links the subject "Catching fish" with the predicate "one of the oldest pastimes."

Therefore, the correct answer is D. Verb.