Which of the following statements is true? a. lungs are strengthened through cardiovascular exercise. b. regular exercise softens bones. c. psychiatrists avoid recommending exercise as a way of dealing with depression. d. inactive people find it easier to change lifestyle habits than active people.

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

20 points and brainlist 1. london has suffered from terrible air pollution for at least seven centuries. why is the city so prone to its famous “london fog? ” what did london do to get rid of its air pollution? 2. why does air pollution cause problems in developing nations more than in developed ones?

How can an organ, such as the lungs, work for multiple body systems?