OPT:
(1). humans.
(2). density.
(3). Seesaw.
(4). swea.
(5). a fish.
(6). deep.
(7). algae.
(8). otters.

Fact 1: Marine species live mainly in shallow coastal waters. Fact 2: Many species of marine algae are toxic or harmful. Given the two facts above, what lives mainly in shallow coastal waters?
Answer:
(7).