Which dietary change is most likely to increase usable vitamin A intake for someone who currently eats mostly raw spinach (plant source) and little dietary fat?

Add a small amount of dietary fat (e.g., olive oil) to the spinach salad and/or include some animal source of preformed retinol (e.g., a small serving of liver or egg yolk) to increase absorption and provide preformed vitamin A.

Boil the spinach for a very long time to remove water and concentrate beta-carotene, which will always increase its bioavailability regardless of fat presence or whether the source is plant- or animal-based.

Consume more citrus fruit with the spinach since vitamin C will enzymatically convert beta-carotene to retinol in the stomach and therefore boost vitamin A status more than adding dietary fat would.

Increase the volume of raw spinach tenfold without changing fat intake because provitamin conversion efficiency is linear and unaffected by dietary fat or preformed sources; therefore sheer quantity is the only way to raise usable vitamin A.