Evaluate Exponents

To find 20⁴ ÷ 5⁴, we apply the following law of exponent,
a^m ÷ b^m = []m.
So, the given expression can be written as,
20⁴ ÷ 5⁴ = []4.
Hence, 20⁴ ÷ 5⁴ = []4 = [4]⁴.
Therefore, option (b) is correct.