During a descent, which way does the eardrum bulge, and why?

1. 1Outward, because the pressure in the middle ear is higher than the outside air pressure
2. 2Inward, because the outside pressure is higher than the middle ear pressure
3. 3Inward, because the Eustachian tube is fully open
4. 4Outward, because the outside air pressure is lower

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 17: Aeromedical Factors — Middle Ear and Sinus Problems, page 427