Explanation:
The correct preposition to use with "sympathetic" when referring to people is "to."

"Sympathetic to someone" means showing understanding, compassion, or concern for them.

Why the other options are incorrect:
B. at – incorrect; not used with "sympathetic."

C. for – "sympathetic for" is sometimes used, but usually with a situation rather than people (e.g., "sympathetic for their loss").

D. from – doesn't fit at all with "sympathetic."

E. on – not a correct preposition in this context.