Judgement call as to if it was dropped intentionally or not.
However ... You cannot intentionally drop a ball. Immediate dead ball. batter out. Runner returns to base at TOP.
Rule 5 Dead Ball - Suspension of Play SECTION 1 DEAD BALL ART. 1 . . . Ball becomes dead immediately when:
j. an infielder intentionally drops a fair fly, fair line drive or fair bunt in flight with at least first base occupied and with less than two outs.