What part of the organ is activated by the manual or keyboard to produce sound?

The part of the organ that is activated by the manual or keyboard to produce sound is the pipes. When a musician presses a key on the organ’s keyboard, it initiates a mechanism that allows air to flow into specific pipes. Each pipe corresponds to a particular pitch or note, and the flow of air causes the pipe to vibrate, producing sound.

In contrast, the other components of an organ play different roles. The strings are not involved in traditional pipe organs; rather, they are relevant in string instruments. Hammers also do not apply to pipe organs; they are associated with instruments like pianos, where hammers strike strings to create sound. Bellows are crucial for providing the air necessary for sound production, but they do not directly produce a tone when activated by the keyboard. Instead, their function is to ensure that air reaches the pipes effectively. Thus, the pipes are the key elements that produce sound upon activation by the manual or keyboard.