Which of the following is a true statement about the risk of getting an sti as a teen? a. teens are more vulnerable to contracting an sti because their immune systems are younger and therefore more resilient. b. teens are more vulnerable to contracting an sti because their bodies are less developed than adults. c. teens are more vulnerable to contracting an sti because they participate in less risky behaviors than adults. d. teens are more vulnerable to contracting an sti because they make up less of the total population in relation to adults.