When a Mixture of Glucose 6-Phosphate and Fructose 6-Phosphate Is $\Delta$

When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase,the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate.Which one of the following statements is most nearly correct,when applied to the reaction below (R = 8.315 J/mol·K and T = 298 K) ?
Glucose 6-phosphate ↔ fructose 6-phosphate

A) ( $\Delta$ G'° is +1.7 kJ/mol.)
B) ( $\Delta$ G'° is -1.7 kJ/mol.)
C) ( $\Delta$ G'° is incalculably large and negative.)
D) ( $\Delta$ G'° is incalculably large and positive.)
E) ( $\Delta$ G'° is zero.)