Given how complicated the derivative,

looks, integrating it to find
seems futile, and actually not what needs to be done. You're asked to approximate
using a given point and the value of the derivative at any point. To do that, you can use a linear approximation.

which comes from exploiting the mean value theorem (solve for
above to see how)
Then

The closest answer would be B. The reason the listed answer is so far off is because 7 is not so close to 2.