Pollen tube entry triggers male gamete release in angiosperm fertilization

Steps:

• Pollen grain germinates on stigma, forming pollen tube.
• Pollen tube extends through style toward ovary.
• Pollen tube penetrates ovule via micropyle.
• Male gametes exit tube inside ovule for fertilization.

Why B is correct:

• In angiosperms, pollen tube delivers sperm cells directly into the ovule, where double fertilization occurs, as defined by the process entering through the micropyle.

Why the others are wrong:

• A. Ovary: Pollen tube passes through ovary to reach ovule; release happens inside ovule, not ovary.
• C. Stigma: Pollen tube originates from stigma; no entry or release there.
• D. Style: Pollen tube grows through style but male gametes release only after ovule entry.

Final answer: B