The ratio of the risk of disease in exposed individuals to the risk of disease in nonexposed individuals is called:

the darker peppered moth species were favored due to the fact that the industrial revolution had made all the nearby trees a darker color instead of white.

all these collisions do one thing, and that thing is explained in the last option. when dusst, rocks and ice collide, they harden and form giant layers of rocks or hard ice.

d)   to harden materials to form different parts of earth’s layers

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bioteacher101