If S Is a String Over (0 + 1)* Then

Multiple Choice

If s is a string over (0 + 1) * then let n0 (s) denote the number of 0's in s and n₁ (s) the number of l's in s. Which one of the following languages is not regular?

A) L = {s € (0 + 1) *n0 (s) is a 3-digit prime
B) L = {s € (0 + 1) * | for every prefix s' of s, l 0 (s') - n₁ (s') | <= 2 }
C) L={s € (0+1) * | n0(s) - n₁(s) | <= 4}
D) L = {s € (0 + 1) | n0 (s) mod 7 = n₁ (s) mod 5 = 0 }