Which of the following is not included in the post-fertilization event in flowering plants?

All of the following are features of angiosperms except $-$

Select the correct option regarding the number of structures in a flower, arranged in descending order.

Bisexual flowers which never open are known as:

List the changes observed in an angiosperm flower subsequent to pollination and fertilisation.

Although sexual reproduction is a long-drawn,energy-intensive complex form of reproduction,many groups of organisms in Kingdom Animalia and Plantae prefer this mode of reproduction. Give at least three reasons for this.