When a piece of ebonite rod is rubbed with a fox fur, a charge of -32 × 10⁻¹⁰ C is developed. The number of electrons transferred is...
a. 20 × 10⁻¹⁰
b. 32 × 10⁻¹⁰
c. 64 × 10⁻¹⁰
d. 16 × 10⁻¹⁰