Ripper is essentially of . . . . . . . . mounted.

A Ripper is essentially a crawler-mounted attachment used in surface mining and construction operations. The ripper attachment is designed to break up and loosen hard soil and rock, allowing for easier excavation and removal.

Option A, Tyre, and Option C, Wheel, are not typically used for ripper attachments as they are not stable enough for heavy-duty excavation work.

Therefore, the answer to this question is Option B, Crawler.