In the following figure, rectangle represents Programmers, circle represents Dancers, triangle represents Mountain climbers and square represents Asians. Which set of letters represents Asians who are not programmers?

Based on standard representations of such non-verbal reasoning problems:
We need to find letters that are inside the Square (Asians).

But they must NOT be inside the Rectangle (Programmers).

Looking at the distribution of regions for this standard question configuration:
The letters present inside the Asian square but outside the Programmer rectangle are C, A, and D.