How does the development of external genitalia differ from the development of the internal ...

How does the development of external genitalia differ from the development of the internal reproductive structures?
 
  a. Reproductive structures are influenced by hormone levels; genitals are not.
 b. Reproductive structures for males and females develop from a single unisex structure; genitals develop from separate Wolffian and Mllerian structures
  c. Genitals for males and females develop from a single unisex structure; reproductive structures develop from separate Wolffian and Mllerian structures.
  d. Genital development is controlled by estrogen; the reproductive structures are controlled by androgen.