This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to increase bdnf
Try biking.
Biking is a cardiovascular exercise that, if done regularly, will increase your bdnf. Bike three to four times a week for 30 minutes to an hour.

Pick from:
[I] Make sure to incorporate 10 to 20 minutes of fast-paced biking to increase your heart rate further. Bike around your neighborhood or local park.
[II] Biking will improve your cardiovascular muscle abilities, including improved strength. Walk on a treadmill for 30 to 60 minutes with the solar psi machine.
[III] If your conditions are serious or there is discomfort in your joints, wear loose-fitting, fashionable clothing such as long sleeves and underwear. A cycling backpack can help improve your posture.
[IV] Another type of cardiovascular exercise is jumping on your bike to increase your bdnf level. Try running for an hour every day for a week.
The answer is:
[I]