Which of the following is correct? What is the square root of 81?

Sheeraz Ahmed graduated from National University of Modern Languages Islamabad in 2019, currently he is CSS Aspirant, and he also appeared in Sindh Public Service Commission (SPSC), Federal Public Service Commission (FPSC) for the purpose of recruitment. At our site Sheeraz publishes the Important MCQs to help students and Job Seekers.