What is the common factor in the expression: 5x^2+20x+30 A 2 B 3 C 5 D 10

To find the common factor in the expression $5x^{2}+20x+30$, we need to identify the greatest common factor (GCF) of the coefficients.<br /><br />The coefficients in the expression are 5, 20, and 30. We need to find the largest number that divides all three coefficients evenly.<br /><br />The factors of 5 are: 1, 5<br />The factors of 20 are: 1, 2, 4, 5, 10, 20<br />The factors of 30 are: 1, 2, 3, 5, 6, 10, 15, 30<br /><br />The common factors of 5, 20, and 30 are 1, 5, and 10. The greatest common factor is 5.<br /><br />Therefore, the common factor in the expression $5x^{2}+20x+30$ is 5.<br /><br />The correct answer is C.