Options :

100

10

1
 \frac{1}{10}
 \frac{1}{100}
Answer: E
Explanation:
Given that,
Reciprocal of the sum
x and y is equal to 10
i.e.,
\frac{1}{x+y}=10
Square of the sum of x and y = \left(x+y\right)^2=\frac{1}{100}
Hence the answer is E.