Final answer:
The best proof of Asha's conjecture is choice C, which states that the perimeter of a square (4n) with odd integer sides is even because multiplying by four (an even number) results in an even number.
Step-by-step explanation:
The perimeter of a square is calculated by adding all four sides together. Since a square has equal sides, if one side is an odd integer, the perimeter is four times this odd integer. The proof of Asha's conjecture that the perimeter of a square with odd integer sides is always even should fundamentally focus on the properties of adding odd numbers and the result of multiplying an odd number by an even one (in this case, four).
Choice C provides the best proof of Asha's conjecture: Let n be an odd number. Because 4n is a multiple of 2, it is an even number. This statement directly applies the mathematical rules that multiplying an odd integer by an even integer (four, in this case) results in an even product, thereby resulting in an even perimeter.