Explanation
$$1 \times 1 = 1$$
$$2 \times 2 = 4$$
$$3 \times 3 = 9$$
$$4 \times 4 = 16$$
$$5\times 5 = 25$$
All are square numbers, so they are perfect squares.
Therefore, A is the correct answer.
Please disable the adBlock and continue. Thank you.