The answer is D. 10. According to the correct order of mathematical operations, multiplication and division are followed by addition and subtraction. So, to calculate 28 ÷ 7 + 2 × 3, first we will divide 28 by 7 and multiply 2 by 3, and them sum all numbers up: 28 ÷ 7 + 2 × 3 = 4 + 2 x 3 = 4 + 6 = 10.