Danielle applied the distributive property to write the equivalent expressions below. *find the math equation to figure question out;))*

What is Danielle's error?
*Answers* ↓↓↓
A. Danielle used 3 as the factor, which is not common to 15 and 21.
B. Danielle did not correctly divide by the common factor to get (4 + 8).
C. Danielle did not apply the correct operations to the expressions.
D. Danielle wrote two expressions that are not equivalent.