What type of circuit is represented in the given figure, and which statement best describes its operation?

• It is a tristate inverter. When the ENABLE input is HIGH, the output is effectively an open circuit—it is neither LOW nor HIGH.
• It is a programmable inverter. It can be programmed to function as either an active LOW or an active HIGH inverter.
• It is an active LOW buffer, which can be turned on and off by the ENABLE input.
• None of the above.