What distinguishes Rule 251 from Rule 261 regarding reverse movements beyond block limits?

• A. Rule 251 requires Form D line 2 authority; Rule 261 requires verbal permission.
• B. Rule 251 requires verbal permission; Rule 261 requires Form D line 2 authority.
• C. Rule 251 applies to electric locks; Rule 261 to bolt locks.
• D. Rule 251 allows movement; Rule 261 forbids it.

Answer: (A)

The key idea is the type of authority required to move in reverse beyond block limits. For Rule 251, you need a formal written instruction—Form D line 2 authority—that specifically authorizes the movement beyond those limits and covers the route, timing, and protection. For Rule 261, you rely on verbal permission from the controlling authority, which is a spoken authorization and not the same as a written form. This difference matters because the written Form D line 2 provides a recorded, detailed directive, while verbal permission is a temporary, verbally communicated allowance that must be acted on with the understanding of its conditions. The other options don’t fit because they describe unrelated aspects (such as equipment) or misstate whether movement is permitted.