This is a book the children enjoyed. what's the subordinate clause and it's introduce by what?

A subordinate clause is also known as a dependent clause. It contains both the verb and the subject and commences with a relative pronoun or a subordinate conjunction. The dependent clause doesn't convey the complete meaning of a sentence.

Hence, in the sentence "This is a book the children enjoyed."

In it the subordinate clause is "the children enjoyed" and is introduces by "this is a book." Which acts as independent clause conveying complete meaning of the sentence.

do you have options?

huck's relationship with food is a prominent theme throughout the novel, and during his time on jackson's island and working his way down river, huck revels in and enjoys his ad hoc dining. in the first chapter, we observe huck is ironically trapped in a "civilized" world, when he would prefer to live freely in nature.