Step: 1
4 × (2 × 1), (4 × 2) × 1 illustrates same product. But grouping of factors is changed.
Step: 2
According to associative property of multiplication, changing the grouping of factors does not change the product.
Step: 3
So, 4 × (2 × 1) = (4 × 2) × 1 illustrates associative property of multiplication.
Correct Answer is : associative property of multiplication