Intentionally dropped ball, or not?

[Yuri10]

Hi,

I'm new to this forum so I greet everybody.

This is a question from a test which caused a discussion between me and other umpires.

Here's the question:

R1 at first and one out. The batter attempts to bunt but the ball goes high for a short fly ball in fair territory in front of the home plate. F2 makes the catch and intentionally drops the ball. What happens?

a) Nothing, the ball is live and in play and the runners may advance at their risk.

b) The umpire calls "Time" and enforces the intentionally dropped ball rule. The batter is out and the runner returns at first.

I'm for answer b, cause rule 6.05 (l) doesn't exclude the bunt, but other umpires are for answer a cause they say this situation is like the infield fly, even if I can't found this on the rulebook.

P.S.
Sorry for my poor english.