What type of gate is an AND gate with an inverter at the output?

An AND gate produces a high output (1) only when all of its inputs are high (1). When you add an inverter to the output of an AND gate, it negates the output of this gate. This means that the output will now be low (0) when the AND gate would normally output high (1), and vice versa.

This function matches the behavior of a NAND gate, which is specifically designed to output low only when all inputs are high. Therefore, when an inverter is used with an AND gate, it effectively transforms the AND gate into a NAND gate, because it inverts the AND operation's output. This characteristic is fundamental in digital logic, where NAND gates are widely utilized due to their versatility in forming other types of gates and circuits.

In summary, when an AND gate is followed by an inverter, the combined effect is that of a NAND gate, making it the correct answer.