26. Highly susceptible populations include:
 a. Younger than 5, older than 65, and immune compromised
 OB. 
 b. Older than 5, younger than 65, and immune compromised
 OC. 
 c. Younger than 5, older than 45, and immature
 OD. 
 d. Younger than 5, older than 65, and physically disabled