There are 7 essential nutrients. They are:
water
fiber
protein
fat
carbohydrate
vitamins
minerals
Take your pick of any two.
Diversity in the types of foods eaten, and lots of fresh water.
inadequate ingestion of nutrients needed for proper metabolism (Omega 3 and vitamin D are two biggies in the developed world), excess consumption of junk carbs...
proper hand-washing depends on waht two things?
Many things...Two of them are, diet and exercise.
There are more than two, but fiber and water are an important two !
Proper nutrition and proper exercise.
Glucose and oxygen
Two eggs and Two Sperm.
calcium and phosphorus
They needed a keep because that was the strongest part of the castle and the portculis.
soil and sunlight
Plants and Animals!
Heat and Alkenes