What type of ice is formed by ice crystals from sublimation?

Frost is formed through a process known as sublimation, where water vapor transitions directly from a gas to a solid without first becoming a liquid. Under the right conditions, such as during cool nights when humid air comes into contact with surfaces that are below freezing, the water vapor in the air deposits as frost. This is why frost is predominantly composed of ice crystals that have formed through sublimation.

Clear ice forms differently, primarily from the freezing of supercooled liquid water droplets that freeze upon contact with surfaces. Rime ice, on the other hand, forms when supercooled water droplets freeze quickly on contact with objects, resulting in a more opaque appearance. Mixed ice is a combination of different types of ice, often seen when conditions vary, but frost itself is specifically linked to the sublimation process, making it the right answer in this context.