Find the GCF of the coefficients 84 and 210 by prime factorization, showing the factors used.

• A. $84=2^2\cdot 3\cdot 7$
• B. $42=2\cdot 3\cdot 7$
• C. $210=2\cdot 3\cdot 5\cdot 7$
• D. $21=3\cdot 7$

Answer: (B)