It erupts more often I think im not sure
I'd guess b on this one. I don't know the definition of watershed, but the amazon is a pretty big expanse of water "stretching" a long way (albeit that water doesn't stretch).
Answer:
Bathymetry
Explanation:
Bathymetry is the study of underwater depth of ocean floors or lake floors. Basically bathymetry is the underwater equivalent to topography