The distance between town X and Y on a topographic map is 10cm. What will be the actual distance on the ground given a map scale of 1:100,000?

Map distance ($D_m$) = $10 \text{ cm}$
Map scale = $1:100,000$ (This means $1 \text{ cm}$ on the map represents $100,000 \text{ cm}$ on the ground).

Actual distance ($D_a$) = Map distance $\times$ Denominator of the scale

We know that $1 \text{ m} = 100 \text{ cm}$ and $1 \text{ km} = 1000 \text{ m}$.
Therefore, $1 \text{ km} = 1000 \times 100 \text{ cm} = 100,000 \text{ cm}$.

The actual distance on the ground is $\text{A. 10 km}$.