In seed plants, what is an important difference between gymnosperms and most angiosperms?

a. gymnosperms rely on animals to carry pollen from the female gametophyte to the male gametophyte, while angiosperms rely on wind.
b. gymnosperms require water for sperm to travel from the male gametophyte to the female gametophyte, while angiosperms do not rely on water for fertilization.
c. in gymnosperms, male gametophytes and female gametophytes are produced in different structures, while in angiosperms they are usually produced in the same structure.
d. both gymnosperms and angiosperms produce seeds on the scales of cones, but angiosperms have flowers.