Which of the following has maximum angle strain?

a) Cyclopropane
​b) Cyclobutane
​c) Cyclopentane
​d) Cyclohexane

More the number of carbon atom more will be the stability and has less angle strain. Thus cyclopropane has less stability and has more bond angle strain
$$\begin{gathered} Bond angle strain of cyclopropane = \frac{1}{2}[{109}^0{28}^{\text{'}} - bond angle of the cyclopropane] \\ = \frac{1}{2}[{109}^0{28}^{\text{'}} - 60] = \frac{{49}^0{28}^{\text{'}}}{2} = {24}^0{58}^{\text{'}} \\ Bond angle strain of cyclobu\tan e = \frac{1}{2}[{109}^0{28}^{\text{'}} - bond angle of the cyclobu\tan e] \\ = \frac{1}{2}[{109}^0{28}^{\text{'}} - 90] = \frac{{19}^0{28}^{\text{'}}}{2} = 9^0{58}^{\text{'}} \\ Bond angle strain of cyclopen\tan e = \frac{1}{2}[{109}^0{28}^{\text{'}} - bond angle of the cyclopen\tan e] \\ = \frac{1}{2}[{109}^0{28}^{\text{'}} - 108] = \frac{1^0{28}^{\text{'}}}{2} =0.{58}^{\text{'}} \\ Bond angle strain of cyclohexane = \frac{1}{2}[{109}^0{28}^{\text{'}} - bond angle of the cyclohexane] \\ = \frac{1}{2}[{109}^0{28}^{\text{'}} - 120] = \frac{- {10}^0{32}^{\text{'}}}{2} = - 5^0{16}^{\text{'}} \end{gathered}$$