In the first pair, the sum of the numbers inside the parentheses is 1 + 3 + 6 = 10.
The square of this sum is 102 = 100.
In the second pair, the sum of the numbers inside the parentheses is 2 + 3 + 5 = 10, and the square of this sum is also 102 = 100.
Conclusion: Thus, the correct answer is (A) 100.