Asubstance that speeds up the rate of a chemical reaction is called
a. a catalyst
b. a substrate.
c. an enzyme.
d. both a and c

A substance that speeds up the rate of a chemical reaction is called a catalyst. Since an enzyme and a catalyst both speed up the reaction, both would be correct. 

 d. Both A and C

That result from subduction of oceanic plates beneath lighter continental plates. most of the earth's volcanoes are located around the pacific ring of fire because that the location of most of the earth's subduction zones.