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.) Estrogen does not need to cross the cell membrane to get to the nucleus.
B.) travel using a transport protein to cross the cell membrane.
C.) travel through the cell membrane and bind to an intracellular receptor inside.
D.) bind to a membrane receptor on the cell's surface.