I think it is erosion (2) because erosion removes soil, rock, and dissolved material.
<span>"they form a cyst: a hard covering is formed around the protozoan and metabolic rate is slowed"</span>
U mean y not what deaar!!
The correct answer is option (d) that is dizygotic twins.
The dizygotic twins also known as non-identical twins or fraternal twins, that is, two siblings who come from distinct eggs or ova, which are discharged at the similar time from an ovary and are fertilized by different sperm.