Using and are two ways you can avoid gender biased language.
a. plural subjects; masculine and feminine pronouns
b. general subjects; masculine and feminine pronouns
c. single subjects; masculine pronouns
d. plural subjects; feminine pronouns

I think the correct answer is B. Using general subjects and masculine and feminine pronouns are ways to avoid gender biased language. General subjects can pertain to a male and female. Also, including both masculine and feminine pronouns in a statement will aid gender equality.