What events caused the formation of most islands in the south pacific?

I think it is volcanic activities that caused the formation of most islands in the South Pacific. This part of the globe is known to contain the pacific ring of fire where most volcanoes can be found. The eruption of these volcanoes might caused the formation mass of soils which turns into islands through time.

option a is correct i.e.

only sodium ions can pass through the membrane.

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.

He should put sand around the spill in order to contain it so that it won't spread