Immature B cells have:
a. Four types of defense mechanisms on their cell membrane
b. Several kinds of defense mechanisms on their cell membrane
c. One specific kind of defense mechanism on their cell membrane
d. No defense mechanisms on their cell membrane

How does drinking alcohol or using drugs put a person at risk for hiv infection? a. they improve judgment, which makes it more likely for people to engage in risky behavior. b. they impair judgment, which makes it more likely for people to engage in risky behavior. c. they impair judgment, which makes it less likely for people to engage in risky behavior. d. they improve judgment, which makes it less likely for people to engage in risky behavior.