Chapter 23 - Mirrors and Lenses - Learning Path Questions and Exercises - Multiple Choice Questions - Page 804: 4

(c) equal to +1

The lateral magnification is given by $-\frac{d_{i}}{d_{o}}$ where $d_{i}$ is distance of image from mirror and $d_{o}$ is distance of object from mirror. Since, the sign of $d_{o}$ is opposite of that of $d_{i}$ so magnification is +1.