Concept:The product of powers with the same base is the base raised to the sum of the exponents.Explanation:Step 1: Write the product as A21⋅A41⋅A81⋯Step 2: Using am⋅an=am+n, the product equals A21+41+81+⋯Step 3: The exponents form an infinite geometric series: first term a=21, common ratio r=21.Step 4: Sum of the series S=1−ra=1−1/21/2=1.Step 5: Therefore, the product is A1=A.Answer:A