The carpel houses the ovary in flowering plant reproduction

Steps:

• Identify the female reproductive parts of a flower: pistil or gynoecium, which includes the carpel.
• Recall that the carpel consists of three main parts: stigma, style, and ovary.
• Note that the ovary is the basal swollen part of the carpel where ovules develop.
• Confirm that no other listed structure encloses or contains the ovary.

Why B is correct:

• By definition, the carpel is the female organ of a flower that encloses and protects the ovary, which develops into fruit after fertilization.

Why the others are wrong:

• A. The anther is the male structure on the stamen that produces pollen.
• C. The ovule is a structure inside the ovary, not containing it.
• D. The pollen grain is the male gametophyte carried by wind or pollinators.

Final answer: B