Solution: Triple fusion occurs when two polar nuclei and a sperm nucleus fuses within the embryo sac of flowering plants. The events that take place in triple fusion are;

• The pollen grains get dusted on stigma which leads to germination, which gives rise to a pollen tube that enters the ovule.

• The pollen tube passes into one of the synergids where it releases two male gametes.

• One out of the two gametes fuses with the egg nucleus and forms a zygote.

• The other remaining gamete fuses with the two polar nuclei located in the central cell and forms a triploid endosperm nucleus.

The nuclei involved in triple fusion are:

• A male gamete or sperm nucleus

• Two polar nuclei