Based on the picture, hill x is higher than hill y beca5 if hill why were higher the car would a. come to a complete stop at the top of hill y.
b. require additional mass to go over hill y.
c. have excess kinetic energy when going over hill y.
d. require additional kinetic energy to go over hill y.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.

it's c. (to reduce the greenhouse effect/carbon gasses)