What is an aerodynamic stall of an aircraft wing, and what primarily causes it?

1. Flow separation and a substantial loss of lift when the wing's critical angle of attack is exceeded
2. The structural failure of the wing spar under high G-loads during maneuvering
3. The engine flameout due to interrupted airflow at high angles of bank
4. The compressibility effects of approaching Mach 1 during a high-speed descent