Estrogen, a hormone, is released by the ovaries. Once released, it travels to cells where it has an influence on sexual development. In order for estrogen to achieve its purpose, it must:
(A) - Travel through the cell membrane and bind to an intracellular receptor inside.
(B) - Bind to a membrane receptor on the cell's surface.
(C) - Estrogen does not need to cross the cell membrane to get to the nucleus.
(D) - Travel using a transport protein to cross the cell membrane.