Where do most major earthquakes occur ?
(1) in the continental interiors
(2)at the mantle-core boundary
(3) randomly over earths surface
(4) in specific earthquake belts within the crust

In the continental interiors.

Explanation:

Earthquakes occur in the crust or upper mantle, which ranges from the earth's ... very large, shallow subduction zone earthquakes such as the Sumatra 2004 M9.1 event, ... Within continents, and along continental plate boundary transform faults such as ... Accurately determining the depth of an earthquake is typically more .

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.

looks like the answer is     c     to me!