Final answer:
The correct application of the associative law of multiplication to the expression (42 · 16) · 10 results in 42·(16·10), which is option B.
Step-by-step explanation:
The question involves the application of the associative law of multiplication, which allows us to change the grouping of the factors in a multiplication problem without changing the product. Applying this law to the expression (42 · 16) · 10, we can group the numbers differently without altering the result. A correct application of the associative law would give us option B: 42·(16·10), which is simply a regrouping of the factors.