_____________ property specifies whether the mask should scroll or stay fixed when the page is scrolled.

The correct answer is: C. mask-attachment

The mask-attachment property specifies whether the mask should scroll or stay fixed when the page is scrolled. It can have the following values:

• scroll: The mask scrolls with the page.
• fixed: The mask stays fixed in place.

The mask-image property specifies the image to use as a mask.

The mask-box-image property specifies the box model for the mask image.

The mask-origin property specifies the origin of the mask image.

Here is an example of how to use the mask-attachment property:

“`css
.container {
width: 500px;
height: 500px;
background-color: blue;
}

.mask {
width: 100%;
height: 100%;
background-color: red;
mask-attachment: fixed;
}
“`

In this example, the mask will stay fixed in place when the page is scrolled.