Please help need asap.. it’s for anatomy and physiology lab i need to study

Christopher came down with chicken pox after spending time in his child’s day care. the chicken pox represents what link in the chain of transmission in this scenario?

Based on the chart, what are the three most effective methods to protect against pregnancy?

In which way does nicotine cause addiction? by stimulating the brain’s pleasure center by increasing blood-sugar levels by decreasing dopamine levels by reducing depression and anxiety