Toxic gases enter earth due to

Explanation:

Carbon dioxide (CO2) is the primary greenhouse gas emitted through human activities

Explanation:

But burning they can be produced mainly plastic

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

clumped distribution, because you'de have all of the population gathered in a relatively small are.

it's the most common because it provides protection and a mate for reproduction

example: humans, seeweed, cattles, etc.