26 (Refer to FAA-CT-8080-2G, Figure 20, area 3.) With ATC authorization, you are operating your small unmanned aircraft approximately 4 SM southeast of Elizabeth City Regional Airport (ECG). What hazard is indicated to be in that area?
C. Unmarked balloon on a cable up to 3,008 feet MSL.
This is correct.
If there's an easier question on the exam, I haven't found it.
Generally, altitudes shown on a VFR Chart are given in MSL.  If provided, elevations in AGL are shown in parenthesis:
In this example, the top of this radio tower is 1548 ft MSL, (1534 ft AGL).
Why is this omportant to the Part 107 Drone Pilot?
Your drone On-Screen Display (OSD) shows the altitude above launch (0 ft AGL) based on the barometric altimeter aboard the aircraft, usually integral within the flight controller.  It important for the pilot to be aware of the AGL of the tops of marked hazards as well as the floor of restricted airspace, which is given in MSL.
Go to:
What is this symbol?
Sometimes I find things on the chart that aren't described anywhere.  The symbol inside this VFR Waypoint is one of those.  It does not appear anywhere in the Pilot's Handbook of Aeronautical Knowledge, or the FAA Aeronautical Chart User's Guide, or the legend on the sectional chart that contains this symbol.
Treetop.Academy is operated by MannMade Digital Video (www.mmdv.com)
Treetop.Academy is operated by MannMade Digital Video (www.mmdv.com)