Answer:
Option 2nd is correct
Associative Property of Multiplication
Explanation:
Associative property of multiplication :
For a, b and c in R we have;

As per the statement:
Given the expression:

By definition of associative property of multiplication we can rewrite this as:

⇒

Therefore, the Associative Property of Multiplication could be used to rewrite 3x ⋅ (7y ⋅ 4) as (3x ⋅ 7y) ⋅ 4