A Prohibited Area on a sectional chart is depicted with:
AA blue hatched border and a 'P-' identifier (e.g., P-40, P-56)✓
BA solid red line bounding a circle
CA dashed purple line
Why →Prohibited areas on sectional charts are depicted with blue hatched borders and labeled with P-prefix identifiers. P-40 covers Camp David; P-56 covers the White House and U.S. Capitol. Flight is prohibited for all aircraft, including sUAS, unless specifically authorized.
The trap →The solid red line answer uses red, which is not a sectional convention. The dashed purple line answer describes an MOA-style hatching pattern with the wrong color.
Field note →Commit the few famous P-numbers to memory: P-40 (Camp David), P-56 (Washington DC area), P-49 (Bush Ranch, Texas). Students occasionally see these on exam questions.
SOURCE → FAA Aeronautical Chart User's Guide; Advisory Circular 91-63CHECKED JUL 16ACS II.A.K3EASY