The postfix expression equivalent to the prefix expression * + a b - c d is

Given prefix expression: * + a b - c d

The outermost operator is *, so the expression is:
(+ a b) * (- c d)

Convert each part to postfix:
+ a b -> a b +
- c d -> c d -

Now place * after the two postfix parts:
a b + c d - *

Therefore, option A is correct.