What is a type of question to give a command

The most effective way to provide children with safety messages is to a. not allow them to explore new environments. b. role play what not to do. c. clearly explain the correct way to do things. d. have a safety-themed day once each year.

Nina has the flu and a high fever. her immune system is exhibiting the line of defense. this defense is part of immunity.

What is the function of the retina?