What occurs immediately after pushing switch S1 in the control circuit?

The correct answer reflects the immediate action of the control circuit when switch S1 is pushed. In a typical control circuit setup involving pneumatic or hydraulic systems, the first action taken in response to activating a switch often involves changing the state of the equipment associated with that switch.

In this context, pushing switch S1 is expected to initiate a sequence of actions controlled by the circuit's logic. If the question specifies that cylinder 1A retracts immediately after S1 is activated, it indicates that the circuit is designed so that the initial response is to draw the cylinder back. This response could be due to the design of the control logic, which routes power or signal to the valve controlling cylinder 1A.

Other options imply actions involving either extending the cylinder, closing a valve, or opening another valve at varying speeds. However, the immediate action that occurs right after the input from switch S1 is focused on the state change of cylinder 1A itself, confirming that the system is designed to retract it upon that specific initial input. This kind of sequential action is typical in systems where control switches dictate immediate changes in the operational state of components like valves and cylinders.