Which of the following refers to how well a measure or research design does what it purports to do?

According to Robert Selman, the concept of trust appears for the first time during friendships among children of about what age?

a. 6 years old b. 8 years old c. 10 years old d. 13 years old

If you were to eliminate 500 calories from your daily diet, you would likely

A) lose a constant amount each day until you stopped losing weight. B) automatically decrease your exercise, and your weight would stay about the same. C) initially lose weight, but the amount lost each day would decline until a new stable weight was reached. D) produce less heat and lose no weight. E) keep losing weight until you terminated your diet.