As this happens over twelve seconds, you would take the total difference in velocities and divide it by twelve to find the change per second
44.0 m/s - 2.0 m/s = 42.0 m/s
42.0 m/s / 12 s = 3.5 m/s2
the acceleration of the rock would be 3.5 m/s2
B. Brittle Star is an echinoderm that moves by waving its arms.
Brittle star is a spiny, hard-skinned, long-armed animal, related to sea star, that lives on rocky sea floor, from shallow areas to the deepest areas. It uses its flexible arms for locomotion.