A two-stage air compressor raises pressure in two steps instead of one, so that the air can be cooled in between. The flow path is: atmosphere → Low-Pressure (LP) cylinder → intercooler → High-Pressure (HP) cylinder → delivery/receiver.

1. The LP cylinder draws in atmospheric air and compresses it partially, raising both its pressure and its temperature.
2. This hot, partly compressed air is then routed to the intercooler, a heat exchanger where it is cooled (ideally back to the inlet temperature) at essentially constant pressure.
3. The cooled, denser air then enters the HP cylinder for the second stage of compression, and finally passes to the air receiver tank.

So immediately after leaving the LP cylinder the air goes to the intercooler, which is the correct answer.

The reason intercooling matters: cooling shrinks the air's volume before the second stage, which brings the compression closer to isothermal and reduces the work needed by the HP cylinder, improving efficiency and lowering delivery temperature. The air does not go back to the atmosphere (that would waste the work already done), it does not pass directly to the HP cylinder (that would skip the very intercooling that justifies two-staging), and it does not go straight to the receiver tank, since it has not yet reached full delivery pressure.