Developmentally appropriate practices are based upon knowledge of

a. child development and research.

b. early childhood education models.

c. your center's goals.

d. government regulations.

Any practices should best be based on a research - this is the correct answer. (a. child development and research) Research is the best source of actual knowledge, rather than people's best guesses (people's best guesses might lead government regulations, but it would be better if they also followed research results.).