Which statement about viruses is correct? viruses cannot change which species they infect. viruses can mutate to infect new species. bird viruses can never infect mammal species. plant viruses only infect plant species that have rna.

The second statement is correct.  Viruses can infect all cellular life forms, but each cellular species can be infected by own limited specific range of viruses. Most viruses that harm animals can not harm humans. But, some viruses can infect different species of mammals, for example both bats and humans can be infected be rabies.

the correct answer is - d. china has a large and growing population.

the fact that china has a large (the biggest) population, and it is still growing, doesn't hinder the agriculture production in the country. in fact, it can for increased production in the agriculture, since there's more labor force, as well the sheer mass of people produces lots of scientists that come up with new inventions as to how to improve this sector. nice example is the inner mongolia region in china, in general dominated by the gobi desert, but few scientist came up with a nice idea as to how to make the region productive by using plants that are very resistant to droughts, so lots of people have been employed, and the region is becoming greener and greener each year, and the production of food in this region is also increasing.