Answer : The correct answer will be,

Explanation :
Significant figures : The figures in a number which express the value -the magnitude of a quantity to a specific degree of accuracy is known as significant digits.
The rule apply for the addition and subtraction is :
The least precise number present after the decimal point determines the number of significant figures in the answer.
The given expression is:


In the given expression, 4.392 has 4 significant figures, 102.40 has 5 significant figures and 2.51 has 2 significant figures. From this we conclude that least precise number present after the decimal point is 2.
Thus, the answer will be
