The correct answer is option A. -80 feet.
To estimate the total change in distance from the group of students' original position at the surface, we consider the descent of 51.87 feet followed by an ascent of 28.95 feet. Adding these two values gives the approximate total change in distance.
Calculating this yields:
Rounding to the nearest ten, the best estimate for the total change in distance is 80 feet.
Among the provided options:
A. - 80 feet
B. - 50 feet
C. - 20 feet
D. - 30 feet
The best estimate for the total change in distance from the group of students' original position at the surface is option A, -80 feet, as it is the closest rounded value to the calculated estimate.