3. the flu virus changes every year. what is the effect of these changes?\n\n- healthy people get sick…

3. the flu virus changes every year. what is the effect of these changes?\n\n- healthy people get sick because it is so unpredictable.\n- doctors are unable to diagnose severe cases of the flu.\n- many people can’t protect themselves by using soap and water.\n- people build up an immunity to all the different types of virus.
Answer
Brief Explanations:
Let's analyze each option:
- Option 1: Flu virus changes (antigenic drift/shift) make it unpredictable, so even healthy people can get sick as immunity from previous strains may not work. This aligns with how flu mutations affect susceptibility.
- Option 2: Doctors can diagnose flu (via tests/symptoms), severity diagnosis isn't hindered by virus changes. Eliminate.
- Option 3: Soap/water fight bacteria, not virus changes. Virus mutations don't affect soap/water's role (they're for hygiene, not virus evolution). Eliminate.
- Option 4: People don't build immunity to all flu types; mutations create new strains, so immunity to old strains doesn't work for new ones. Eliminate.
Answer:
A. Healthy people get sick because it is so unpredictable.