A factor of 36 divides 36 exactly with no remainder.<br><br>&bull; 36 ÷ 2 = 18 → 2 is a factor<br>&bull; 36 ÷ 6 = 6 → 6 is a factor<br>&bull; 36 ÷ 36 = 1 → 36 is a factor<br>&bull; 36 ÷ 5 = 7 remainder 1 → 5 is NOT a factor<br><br>Final Answer: A: 5