Asteroids vary greatly in size and are mostly made up of frozen water and gas. This one is true.
They are said to be "mostly formed of ice and gas" as they rarely can be found consisting of stone, nickel and iron. These are extremely dangerous in our Universe.
Below are the choices, the answer is no. 3:
1) The virus was descended from a common ancestor of bird, pig, and human flu viruses.
2) The infected individuals happened to be infected with all three virus types.
3)Related viruses can undergo genetic recombination if the RNA genomes mix andmatch during viral assembly.
4)The human was likely infected with various bacterial strains that contained all three<span>RNA viruses.</span>
<span>The mammalian sperm cell consists of a head, a midpiece and a tail. The head contains the nucleus with densely coiled chromatin fibres, surrounded anteriorly by an acrosome, which contains enzymes used for penetrating the female egg.</span>
The layer of the atmosphere where most of the weather happens is called the troposphere.
