5 (Refer to FAA-CT-8080-2G, Figure 59, area 2.) The chart shows a gray line with "VR1667, VR1617, VR1638, and VR1668." Could this area present a hazard to the operations of a small UA?
Why is the MTR width in nautical miles?
In general, ground-based measurements are in Statute miles and airborne measurements are in nautical miles. For example, visibility is a ground-based observation and will be stated in statute miles. Almost all aeronautical navigation and instrumentation is based on the nautical mile.

Why is this important to Drone Pilots?
MTR's are a safety concern for all pilots because contact with anything flying more than 250 knots would be bad. Fortunately, when outside of the Military Operating Areas (MOA), military aircraft blend into the national airspace quite well. If you will be flying a drone near an MTR, you can call Flight Service (1-800-WX-BRIEF)

Which FSS you're routed to is determined by the number you're calling from. This works well if you're on a landline or calling from your cell phone's local calling area, but what if you're away from your home area code? Luckily, the FAA has published the numbers for all the FSSs, all are toll-free if you've got one of those ancient plans without free long distance.
Most MTR minimum low altitude operations are governed by FAA and military rules and are mostly above 500 ft., making this the mostly correct answer. 14 CFR§91.119 Minimum safe altitudes: General, and AFR 60-16 : General Flight Rules (Airforce Flight Rules) must be complied with by military aircraft, but there are exceptions. For example, military aircraft operating within the boundaries of an MOA (Military Operating Area) can be from the surface up to the MOA boundary.

This question is mostly correct because the MTR's in the image accompanying the question are not inside an MOA, but MTRs below 1500 ft are not charted,. MTRs with no segment above 1,500 feet AGL are identified by four number characters; e.g., IR1206, VR1207. Typically aircraft on the MTRs in this image will be between 500 ft (because of §91.119) and 1500 ft AGL (because of the 4-digit MTR identifier).
If in doubt, call Flight Service (1-800-WX-BRIEF) to ask if the MTR is active.
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This is not the correct answer.
B. Yes, this is a Military Training Route from 1,500 feet AGL.
From the FAA Chart Guide:
Routes at or below 1500’ AGL (with no segment above 1500’) are identified by four-digit numbers; e.g., VR1007, etc. These routes are generally developed for flight under Visual Flight Rules.
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