Question

Triple fusion occurs between
A. Egg and male gamete
B. Male gamete and secondary nucleus
C. Antipodal cell and male gamete
D. Egg and antipodal cell

Answer 1

Double fertilization is a complex mechanism in which one of two sperm cells fuses with the egg cell and form a diploid zygote and the other with two polar nuclei, to form a triploid resulting in the primary endosperm nucleus (PEN) Triploid nucleus formation of endosperms is called triple fusion.

Complete answer:
In order to understand triple fusion, let us first understand sexual reproduction in flowering plants.
A Flower Reproductive Structure:
Androecium
Each stamen consists of two parts, namely, anther and filament. It is the male reproductive portion of a flower, consisting of stamens. The filament is protected by the tip of the anther. Pollen is formed by meiosis here
Gynoecium
It is the reproductive organ of the female. It consists of a pistil and occupies the central thalamus position. The components of the pistil are the stigma style, and ovary. Internally, the ovary develops ovules. Ovules create megaspores via meiosis, which grow into female gametophytes in turn. Egg cells are formed as a result.
Pollination is called the location or movement of pollen in the angiosperm from the anther to the stigma of the same or another flower. Pollination in gymnosperms includes the passage of pollen from the male cone to the female cone. The pollen germinates after transmission to form the pollen tube and the egg-fertilizing sperm.
Double Fertilization
It must germinate and grow via the style to enter the ovule after pollen is deposited on the stigma. There are two cells in the microspores, or the pollen: the cell of the pollen tube and the generative cell. The cell of the pollen tube develops into a tube of pollen that the generative cell passes into. Water, oxygen, and certain chemical signals are necessary for germinating the pollen tube.
If the generative cell divides to form two sperm cells. The pollen tube is directed by the chemicals secreted by the synergies present in the embryo sac; through the micropyle, it reaches the ovule sac. The egg cell is fertilized by one sperm, producing a diploid zygote from the two sperm cells; the other sperm fuses with the two polar nuclei, forming a triploid cell that becomes the endosperm.
Together, these two activities of angiosperm fertilization are known as double fertilization. No other sperm will come in after fertilization is complete. The seed forms the fertilized ovule, while the tissues of the ovary become the fruit, normally enveloping the seed. Embryonic growth commences after fertilization

Thus from the above discussion, it is clear that triple fusion occurs between male gametes and two nuclei thus the correct answer is option B.

Note: Functions of a Flower:
Reproduction of the organism and the species is the main primary function of the flower.
Flowers provide pollen tube growth, pollen base germination, gamete formation, and fertilization. The carpel's ovarian part is delivered into the fruit. After fertilizing, the ovules are converted into seeds. In the case of heterosporous plants, gametophytes often grow within the spores.