World Geography
The knowledge about the topography of the ocean basins has been derived from

seismic surveying
side-scan sonar
All of these
echo sounder

ANSWER DOWNLOAD EXAMIANS APP

World Geography
The Penumbra is

formed by the tangent that intersects between the sun and the moon
the outer portion of the moon's shadow
None of these
both (a) and (b)

ANSWER DOWNLOAD EXAMIANS APP