The Formation Constant for Ag(CN)₂−(aq)is 2 × 10²⁰

The formation constant for Ag(CN) ₂−(aq) is 2 × 10²⁰.At what cyanide ion concentration is [Ag⁺] = [ Ag(CN) ₂−]?

A) 3 × 10−⁴¹ M
B) 5 × 10−²¹ M
C) 7 × 10−¹¹ M
D) 6 × 10−⁶ M
E) 1 × 10¹⁰ M