Asource from which organisms generally take elements is called a/an

a. biotic community.
b. exchange pool.
c. reservoir.
d. food web.

When new rock is added to an oceanic ridge, the magnetized strips on either side of the ridge are evidence of sea-floor spreading. this is because the rocks on the two sides of the ridge o are equal in width and in polarity are polar opposites oare magnetized vary in width but are equal in polarity