Final answer:
Among the groups at risk for TB, people with weakened immune systems have the highest risk due to their compromised ability to fight infections, surpassing the risk levels in children under 5, the elderly, and healthcare workers. The correct option is 3.
Step-by-step explanation:
In assessing which group has the highest risk of tuberculosis (TB), it is important to consider various factors that contribute to vulnerability. The groups identified are children under the age of 5, elderly individuals, people with weakened immune systems, and healthcare workers.
Among these, people with weakened immune systems are generally at the highest risk of developing TB due to their compromised ability to fight off infections. This includes individuals with HIV/AIDS, those undergoing chemotherapy, and people with chronic diseases. Although the other groups such as the elderly and healthcare workers are also at risk, their risk is not typically as high as those with weakened immune systems.
For children under the age of 5, their immune systems are still developing, which does put them at risk, especially if they are in close contact with someone who has active TB. However, this risk is surpassed by that faced by individuals with significantly weakened immune defenses.