part a: which of the following best states a central idea of the letter?

a
love can be painful and challenging, but it is worth the sacrifice.
b
some people simply cannot be understood by others, regardless of the feelings of affection one may have for them.
c
love is so powerful that a mere similarity of temperament can sustain a relationship between two otherwise dissimilar people.
d
retaining one’s passion and enthusiasm is vital to forging successful relationships.