The digits are given below:-

562, 871, 438, 753

If the position of the first and third digits of each of the numbers are interchanged, which of the following will be the sum of the first and the second digits of the third highest number?  

8

Arranging digits according to the question:

265, 178, 834, 357

Hence, third highest would be 265 and 8 be the sum of first and second digits of the number.