Query about Question 15 from "Timed Quant Practice - Easy Section 2 Sample Test #4". HELP

https://www.gregmat.com/quizzes/quiz/timed-quant-practice-easy-section-2-sample-test-4 (Question 15)


For this question, I didn’t count the 6x6 options because the question said rectangular grid. Did I overthink the question. When should i know to take it seriously?

A square is a rectangle.