15. (1) what is an island arc? a. a large wooden boat that ferries animals from one island chain to another. b. a crescent shaped volcanic mountain chain created by plate tectonic volcanism. c. an anomalous electrical charge. d. none of the above.

B

Explanation:

A) not A because that is impractical and cannot be run naturally by geographic means

B) Yes, because the islands are in a crescent shape due to the volcanic activity.

C) not applicable

D) No, because the answer is B

c. seafloor spreading occurs.

d. crust becomes molten rock.

e. denser plates slide under lighter plates.