Even the radio's scratchy static was music.
the auditory (sound) image in this line supports the meaning of the
poem as a whole by showing:

that everyone has a unique taste in music.
how a feeling of happiness can make even an unpleasant sensation
feel pleasant
how there is no radio reception in remote places.
an unpleasant sensation caused by the repetition of the s sound.

throughout history, economists have always thought  ..

c is the answer because first she would blush to make the reader wonder why which they find out in the next line.

basic principle: a pronoun usually refers to something earlier in the text (its antecedent) and must agree in number — singular/plural — with the thing to which it refers. the indefinite pronouns anyone, anybody, everyone, everybody, someone, somebody, no one, and nobody are always singular.