The expression that is equivalent to a perfect square in the options is 34 + 18 ÷ 3².
What is a perfect square?
A perfect square is the number derived when a number is multiplied by itself. For example, 9 is a perfect square because 3 multiplied by 3 is equal to 9.
3 + 2² x 7 = 31
(80 + 4)÷ 4 = 21
34 + 18 ÷ 3² = 36
3²+ 6 x 5 ÷ 3 = 19