The South China Sea lies between Philippines and Vietnam.
Answer:
Letter a shows a Divergent boundary. The plates are moving away from each other.
Letter B shows a Convergent Boundary (from what it looks like cause its kinda hard to tell). The plates move towards each other
Letter C (looks like bc i cant see it very well) transform boundary. The plates move past each other
Explanation:
Volcanoes,erosion,chemical weathering