N₂(g) + O₂(g) ⇄ 2NO(g) K_c = 4

N₂(g) + O₂(g) ⇄ 2NO(g) K_c = 4.8 × 10⁻³¹ 2NOBr(g) ⇄ 2NO(g) + Br₂(g) K_c = 0.50
Given the above equilibrium constant data at 25°C, what is the value of K_c at this temperature for the reaction
2NOBr(g) ⇄ N₂(g) + O₂(g) + Br₂(g) ?

A) 2.4 × 10 ⁻³¹
B) 9.6 × 10 ⁻³¹
C) 1.0 × 10 ³⁰
D) 4.2 × 10 ³⁰
E) None of these choices are correct.