The correct answer is option 'C) Envelope tool'.

The Envelope tool in Adobe Audition allows you to adjust the volume of an audio clip. It is a powerful tool that gives you precise control over the volume levels within a clip. The Envelope tool works by creating volume points that you can manipulate to increase or decrease the volume of specific sections of the audio.

Here is an explanation of the Envelope tool and how it works:

1. Select the Envelope tool:
- In Adobe Audition, the Envelope tool is located in the toolbar on the left side of the interface. It looks like a diagonal line with dots on it.

2. Adjusting the volume:
- Once you have selected the Envelope tool, click and drag on the audio waveform to create volume points. These points represent the volume levels at different positions in the clip.
- You can add multiple volume points to create a smooth curve or adjust the volume in a step-like manner.
- To increase the volume, drag a volume point upwards. To decrease the volume, drag a volume point downwards.

3. Fine-tuning the volume:
- To fine-tune the volume adjustments, you can click and drag on the volume points to move them up or down.
- You can also adjust the shape of the curve by clicking and dragging the line segments between the volume points.

4. Creating fades:
- The Envelope tool can also be used to create fades at the beginning or end of an audio clip. A fade is a gradual increase or decrease in volume.
- To create a fade-in, you can add a volume point at the beginning of the clip and drag it upwards to increase the volume gradually.
- Similarly, to create a fade-out, add a volume point at the end of the clip and drag it downwards to decrease the volume gradually.

By using the Envelope tool in Adobe Audition, you have precise control over the volume levels in an audio clip. You can adjust the volume for specific sections, create fades, and fine-tune the volume adjustments to achieve the desired sound for your audio project.