Two thin lenses are placed in contact on a common axis. Four such pairs are listed in List-I, with the focal length of each lens. Match each pair with the power of the combination in List-II. A dioptre, $\text{D}$, is one per metre. List-I (Focal lengths of the two lenses) A. $+20\ \text{cm}$ and $+20\ \text{cm}$ B. $+25\ \text{cm}$ and $-50\ \text{cm}$ C. $-10\ \text{cm}$ and $+40\ \text{cm}$ D. $+50\ \text{cm}$ and $-25\ \text{cm}$ List-II (Power of the combination) I. $+2.0\ \text{D}$ II. $-2.0\ \text{D}$ III. $-7.5\ \text{D}$ IV. $+10\ \text{D}$