Test cock #1 on a 2" and smaller pressure vacuum breaker is located between the check valve and the:

In a pressure vacuum breaker (PVB) system, the test cock is a crucial component used for testing the operation of the device and ensuring that it is functioning correctly to prevent backflow. The location of test cock #1 relative to other components of the PVB is important for efficient testing and maintenance.

The test cock #1 is specifically placed between the check valve and the inlet shutoff valve #1. This positioning allows for direct access to the water pressure in the system immediately after the check valve, which is essential for determining if the check valve is functioning properly.

In the scenario of a pressure vacuum breaker, the device's primary function is to prevent back siphonage and allow air to enter the system to equalize pressure during a drop. By placing the test cock between the check valve and the inlet shutoff valve, it enables technicians to effectively assess the operation of the check valve. If there is a malfunction, the test can reveal any issues with backflow prevention.

Thus, the choice of the inlet shutoff valve #1 as the correct answer emphasizes the necessity of precise test locations within the plumbing system for proper maintenance and functionality, ensuring the PVB operates as intended.