Despite of the pills which are available, many people still have trouble sleeping

Option A, “Despite of”, is incorrect in this context. The correct phrase should be “In spite of”.

In English, “In spite of” is a preposition used to show that something happens even though something else might have prevented it. “In spite of” is used before a noun, a noun phrase, or a pronoun.

The phrase “Despite of” is not standard English. “Despite” is similar in meaning to “In spite of”, but it is used without “of”.

So, the corrected sentence would be:

“In spite of the pills which are available, many people still have trouble sleeping.”

This means that even though pills are available to help with sleep, many people continue to have trouble sleeping.