Question

The common factor of $3ab$ and $2cd$ is:

• A. 1
• B. -1
• C. a
• D. c

Answer 1

The correct option is A

1

$1,3,a,b,3a,3b,3ab,ab$ are the factors of $3ab$.
$1,2,c,d,2d,2c,2cd,cd$ are the factors of $2cd$.
The two terms have $1$ as a common factor.