Research conducted between 1972 and 2003 found that people of which marital status tend to have the best overall health?

As a man ages, it is likely that his voice will tend to get ________ in pitch, and his ability to hear will deteriorate most for sounds that are ________ in pitch

a. higher; high b. higher; low c. lower; high d. lower; low

Positive reinforcement ______ the likelihood that the behavior preceding it will happen again while negative reinforcement ______ the likelihood that the preceding behavior will happen again

a. increases; decreases c. increases; increases b. decreases; increases d. decreases; decreases