AP BIOLOGY help please!?

E, D, B.

1. D
Answer D is not complete, so it is hard to tell which is the correct answer from first glance--when all else fails, use elimination to determine the correct answer...
A is not correct because most radially symmetric organisms are not quick moving--jellyfish, sea urchins, sea stars, etc.
B is not correct because some radially symmetric organisms do not swim (such as echinoderms)
C is not correct because organisms who can fly are always bilaterally symmetrical.
D--not complete
E is not correct because there are organisms who have radial symmetry who do not have legs (such as sea urchins).


2. D
Organisms with a head/brain/Central Nervous System (CNS) are not sessile (immobile) organisms.

3. E
Arthropoda are insects (who are terrestrial).  Usually when you think of mollusca, you'd think of squids or octopi, but the class 'gastropoda' includes organisms such as snails, who are, obviously, terrestrial.  Organisms in the vertebrata classification have backbones, which includes humans (terrestrial).  Organisms such as crabs are crustaceans, and therefore terrestrial (they can live out of water).  The only other answer is echinodermata, which includes sea stars and sea urchins... None of these organisms live on land, so "echinodermata" is the correct answer.