In petrach's sonnet 292, the sestet opens with the line, “and i live on, but in grief and self-contempt.” the word or phrase which best signifies the beginning of the volta is
and
live on
but
grief and self-contempt

the correct answer is actually BUT because it is the turning point in the sentences Hope this helps

The word or phrase which best signifies the beginning of the volta is but

A volta in literature is the shift or change of thought or emotion

But is a connector of contrast which is helping us to identify the change between I live on that is a positive feeling and in grief and self-contempt that are negative views or thoughts.

The other options don't present any change in any way, we have a noun, a verb and a connector that add information but not contrasting one.

the sentence does not violate the phrase structure second rule (introduced by noam chomsky) because noun phrases consist of a determiner such as a, the or every, and a noun. in the sentence, the noun phrase the cake includes a determiner (the) and a noun (cake).

on the other hand, the first rule indicates that a sentence encloses a noun phrase, followed by a verb phrase. the example sentence can be analysed as follows:

john (n) + ate (v) + the (det) + cake (n).

the answer is "a" although apex might say best book of the year.