Right choice is (c) ampersand
Explanation: ASCII control characters are defined from %00-%1F, these characters are to design control hardware devices. These characters are not used inside URL. NUL, ENQ, ETX, BEL, BS, HT, LF, EOT, CR, DLE, DC3 are some of the control characters. BS is for backspace, NUL is for null character, HT is for the horizontal tab character.