Question

which geologic features would be expected at an oceanic - oceanic convergent boundary?
earthquake activity
continental volcanic mountains
volcanic island arcs
a coastal mountain range

Explanation:

1. Analyze "earthquake activity": Earthquakes occur at various plate boundaries, not unique to oceanic - oceanic convergent boundaries. So this is not the best answer.
2. Analyze "continental volcanic mountains": Continental volcanic mountains form at oceanic - continental convergent boundaries (when an oceanic plate subducts under a continental plate), not oceanic - oceanic. So this is incorrect.
3. Analyze "volcanic island arcs": At an oceanic - oceanic convergent boundary, one oceanic plate subducts beneath another. The subduction zone leads to the melting of the subducting plate, and the magma rises to form a chain of volcanic islands (volcanic island arcs), like the Japanese islands. This is a characteristic feature of oceanic - oceanic convergent boundaries.
4. Analyze "a coastal mountain range": Coastal mountain ranges are typically associated with oceanic - continental convergent boundaries (e.g., the Andes), not oceanic - oceanic. So this is incorrect.

Answer:

C. volcanic island arcs