CH3−CH3>CH2=CH2>CH3−C≡CH>CH≡CH
CH2=CH2>CH3−CH=CH2>CH3−C≡CH>CH≡CH
CH≡CH>CH3−C≡CH>CH2=CH2>CH3−CH3
CH≡CH>CH2=CH2>CH3−C≡CH>CH3−CH3
In hydrocarbons acidity increases as the s character increases. So the acidity order of hydrocarbons is Alkane < Alkene < Alkyne and the acidity of substituted alkyne are less than unsubstituted alkyne due to I-effect. Hence correct order is C2H2>CH3−C2H2>CH2=CH2>CH3−CH3. Option D is correct.