1) The prefix expression + * - 2 3 5 7
scan from right to left
if operand comes push operand on stack
if operator comes evaluate operand1(top of stack) operator operand2
answer comes out to be 2
2) The postfix expression 2 3 + 5 * 7 -
scan from left to right
if operand comes push operand on stack
if operator comes evaluate operand2 operator operand1(top of stack)
answer comes out to be 18
3) The infix expression (2 + 3) * (5 - 7)
This is simple math calculation
answer comes out to be -10
4) The postfix expression 2 3 + 5 7 - *
Apply same procedure as mentioned above for point no 2
answer comes out to be -10
Ans is B
Please correct me if i am wrong