1. Concept used

   The work done against gravity depends only on the change in vertical height, not on the path followed.

   $W = mgh$

   where:

   • $m = 50\,\mathrm{kg}$
   • $h = 20\,\mathrm{m}$
   • $g$ is acceleration due to gravity

2. Case 1

   The body is lifted from the ground to a height of $20\,\mathrm{m}$.

   So, work done against gravity is

   $W_1 = mgh = 50 \cdot g \cdot 20$

3. Case 2

   Even if the body is taken through a different path, the final vertical rise is still $20\,\mathrm{m}$.

   Hence,

   $W_2 = mgh = 50 \cdot g \cdot 20$

4. Ratio of work done

   $W_1 : W_2 = mgh : mgh = 1 : 1$

5. Option check

   • A: $2:1$ ❌
   • B: $\sqrt{3}:2$ ❌
   • C: $1:1$ ✅
   • D: $1:2$ ❌

Therefore, the correct answer is:

$\boxed{1:1}$