"of insects" is an adjective phrase because it's a prepositional phrase that acts as an adjective. It modifies the word "group"; In other words, "of insects" is used to describe the word "group".
The correct answers should be
<span>-the greater amount of leisure available to people</span>
<span>-the growth of the publishing industry
</span><span>-increased literacy rates in the middle class
</span>
People started educating themselves which led to increased amount of reading. Novels were not considered high culture so they were very available to the middle class.
