Mental excess could produce, for its own purposes, the voluntary blindness and deafness of deliberate solitude, the
artificial impotence of asceticism.

In this sentence, voluntary means:
A. dangerous
B. mournful
C. timely
D. willful

both male and female gametes are produced by meiosis of the germ cells. therefore, both male and female gametes are haploid. one male and one female gamete unite during the fertilization to form the diploid zygote. in seed bearing plants, pollen grain is the male gametophyte, which produces sperm cells.

the endomembrane system i think