Which of the following shows a reduction of chromosomes by half?
male gametophyte to flagellated sperm
sporophyte to spores
male gametophyte to spores
female gametophyte to zygote

The correct answer is-  

A sporophyte can be described as the multicellular, diploid phase in the life cycle of plants and alga.

It is the dominant phase in higher plants ( such as angiosperms and gymnosperms) and undergoes alternation of generation with a haploid, gametophyte phase.

Sporophyte produces haploid spores ( having half the number of chromosome as their diploid parent cell) by a process of cell division called meiosis ( also termed as reductional cell division)

The spores fuse to form a dipolid zygote that undergoes mitotic division to produce the sporophyte again.

On the contrary, male and female gametophyte are already haploid.

Thus, second option is the right answer.

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.

sex cells are usually half's then they find another half and make a fertilize egg