Which phraseology clarifies that only the amendment to the route is issued and the rest of the route remains unchanged?

• A. CHANGE ROUTE TO READ (amendment to route)
• B. (Amendment to route), REST OF ROUTE UNCHANGED
• C. AMEND ALTITUDE
• D. AMEND ROUTE

Answer: (B)

The point of this wording is to make the scope of the change crystal clear: only the route is being amended, and everything else in the clearance remains the same. The phrase "(Amendment to route), REST OF ROUTE UNCHANGED" does this explicitly. It flags that there is a modification to the route and, at the same time, confirms that the rest of the clearance stays unchanged, leaving no room for misinterpretation. The other options either imply a broader change (or focus on altitude) or don’t clearly state that only the route amendment applies while the rest remains as issued. This phrasing reduces ambiguity and keeps the pilot’s understanding aligned with the intended adjustment.