Formation of endosperm during double fertilization takes place by

The correct option is C

Two polar nuclei and one male gamete.

The correct option is C.

Explanation for correct option:

1. The formation of the endosperm takes place through the triploid cell.
2. A secondary male gamete fuses with two polar nuclei forming a diploid secondary nucleus which results in the formation of the primary endosperm nucleus (PEN) and triploid cell.

Explanation for incorrect options:

Option A:

1. The ovum fuses with the male gamete to form a zygote.
2. Zygote is diploid in nature.

Option B:

1. Two polar nuclei fuse with one male gamete to form an endosperm.
2. The endosperm is the most common nutritional tissue for the developing embryo in angiosperms.

Option D:

1. The fusion of one male gamete with single polar nuclei is not found in the endosperm foundation.

Final answer: The formation of endosperm takes place by the fusion of two polar nuclei and one male gamete.