Answer:
B. Distributive property.
Step-by-step explanation:
The expression is simplified by expanding it using the distributive property which says for any real numbers [tex]a,b,[/tex] and [tex]c[/tex]
[tex]c(a+b)=ca+cb[/tex]
and upon simplification the expression becomes:
[tex]3x(y-14)=3xy-42x[/tex]