The statement which best illustrates the main theme is that First Love can have a lasting effect on a person. The correct answer thus is A.
Given the references to "First Love", one can infer that the text is culled from the poem First Love by John Clare.
Note that the last two lines of that poem state:
my heart has left-it's dwelling place
and can return to its place no more.
Usually, writers have a key idea around which their stories are centered. They may be values or principles or messages that they want the audience to know. The name for these ideas in literature is called Theme.
Examples of key themes can be:
See the link below for more about themes:
https://brainly.com/question/25841984