It is to transport of two substrates in the same direction across the membrane.

Active transport

Explanation:

To transport the substrate across the membrane it will need energy in the process it's called active transport.

Symport

Explanation:

A symport is he transport of two different molecules or ions in the same direction through a membrane using a common carrier mechanism.

answer; ///i do believe that the correct answer is (c) hold atoms together to form compound;

your answer is "the 1950's"