Pesky Plane

 is the 48th level in Bloons 2, and the 12th level in the Sneak Peaks zone.

Solution
Hit two of the left Ceramic Blocks with four darts. Use the fifth dart to hit the Tack Bloon, which should provide a chain reaction. Since it automatically causes two Bonus Dart Bloons to pop, the two other darts can subsequently be used to pop the one other left Ceramic Block.