a b c d

c

$M = - \frac{v}{u} = \frac{1}{4}$ $ v = -\frac{u}{4}$ $ \frac{1}{v} + \frac{1}{u} = \frac{1}{f}$ $ \frac{-4}{u} + \frac{1}{u} = \frac{1}{30}$ $ \frac{-3}{u} = \frac{1}{30}$ $\Rightarrow u = -90cm$