Given that (d₃ = 3.0 × 10⁻⁴ m) and (n₀ = 5.0 × 10⁻⁵ m) at (t = 0), calculate the rate of the reaction at (t = 0):

a) (2.0 × 10⁻⁴ m/s)
b) (1.0 × 10⁻⁴ m/s)
c) (4.0 × 10⁻⁴ m/s)
d) (5.0 × 10⁻⁴ m/s)