In Order to Measure the Standard Free Energy Change $\Delta$ G $\degree$

In order to measure the standard free energy change, $\Delta$ G $\degree$ , for the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, you set up the reaction at 25 $\degree$ C with 1 M reactants and

A) change the concentration of the product.
B) change the temperature.
C) add 1 M of product.
D) alter the pH.
E) maintain one atmosphere of pressure.