Which statements are true? A. Gravity on Mount Everest is greater than surface g. B. Gravity there is less than surface g. C. A ball thrown vertically and returning after 15 s has speed 75 m/s. D. Such a ball has speed 150 m/s.

The source selects A but incorrectly uses the full flight time as the acceleration time from rest. For a 15 s return flight with g = 10 m/s², launch and return speeds are 75 m/s, so B and C are true. No listed option matches; the source key is retained and flagged.