Crocodiles, bats, whales, and birds have similar limb bones. what do these similarities suggest?
a.
crocodiles, bats, whales, and birds evolved from a common ancestor.
b.
bats and crocodiles share an ancestor with whales but not with birds.
c.
the common ancestor of birds and crocodiles was a whale.

Oceans produce approximately 80 percent of the oxygen our planet needs to support animal life. pollution that reaches the ocean through dumping, oil leaks, runoff, and other processes interferes with that oxygen production and poses a real threat to the oxygen content in our atmosphere. if the oxygen content decreases, it is likely that carbon dioxide will increase. this could have dramatic consequences for life as we know it. which does this passage indicate causes a decrease of oxygen in the atmosphere?