Which of the following hydrocarbon has least C-C bond length ?

C₂H₆ (CH₃-CH₃)------ C-C    Single bond Character
C₂H₄(CH₂ = CH₂)----- C = C Double Bond Character
C₂H₄ $(\mathrm{CH}\equiv \mathrm{CH})$ ----- $(\mathrm{C}\equiv \mathrm{C})$ Triple bond Character
C₆H₆ ------- Intermediate of C=C and C-C bond Character
$\therefore$ least C-C bond length present in C₂H₂