Answer:
They are discussing the B)Semantics of the words.
Explanation:
Semantics is the branch of linguistics that studies meaning. It studies the meaning of words, signs, symbols, and even algorithms.
In this question, Robbie and Gary are having a semantic discussion, because they are arguing about the meaning of the words femenine and feminism, and while Gary's misconceptions about the meaning of these words may be influeced by their morphology and phonetics, the essence of the error he is committing lies in a semantic confusion.