Rs. 4800

Rs. 5000

Rs. 5400

Rs. 5600

B. Rs. 5000

Let the investment in 9% stock be Rs. x.

Then, investment in 10% stock = Rs. (9800 - x).

$\frac{9}{75}\times x=\frac{10}{80}\times (9800-x)$

$\Rightarrow \frac{3x}{25}=\frac{9800-x}{8}$

$\Rightarrow $24x = 9800 x 25 - 25x

$\Rightarrow $49x = 9800 x 25

$\Rightarrow $x = 5000.