An observer with normal eyes views an object with a magnifying glass of focal length 5cm.The angular magnification is A.-6 B.-5 C.5 D.6 [least distance of distinct vision D=25cm]?

The focal length of the magnifying glass is $f = 5 \text{ cm}$.
The least distance of distinct vision is $D = 25 \text{ cm}$.
The formula for angular magnification ($M$) when the image is formed at the least distance of distinct vision is:

$$M = 1 + \frac{D}{f}$$

$$M = 1 + \frac{25 \text{ cm}}{5 \text{ cm}}$$ $$M = 1 + 5$$ $$M = 6$$

The calculated angular magnification is 6. This matches option D.

The final answer is $\text{D. 6}$.