A convex lens acts like a magnifying glass; when you move an object close to the focal point, the image flips and enlarges, just like how a camera lens focuses light onto a sensor.

The lens formula is $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$. With $f = +20 \text{ cm}$ and $u = -30 \text{ cm}$ (sign convention), we get $\frac{1}{v} = \frac{1}{20} + \frac{1}{-30} = \frac{3-2}{60} = \frac{1}{60}$. Thus, $v = 60 \text{ cm}$. Magnification $m = \frac{v}{u} = \frac{60}{-30} = -2$. Note: The question implies magnitude or uses specific conventions; however, purely calculation-wise, $m = -2$. Given the options, there is an error in the provided answer key as the correct value is $-2$.

Always verify the sign of $u$ as negative in lens problems; ignoring this is the most common cause of calculation errors in competitive exams.