Your answer would be C. 6.07 × 10^24.
This is because to add numbers in standard form, we need to get their (×10^x) to be the same, as in, we need to get 7 × 10^22 to be [value] × 10^24.
To convert ×10^22 to ×10^24, we need to divide 7 by 100, as 0.07 × 10^24 = 7 × 10^22.
Now that we have them both with the same power, we can add 6 to 0.7 to get 6.07 × 10^24.
I hope this helps! Let me know if you have any questions because my explanation was a bit strange :)
