Multiple choice

The horse has played a little known but very important role in the field of medicine. Horses were injected with toxins of diseases until their blood built up immunities. Then a serum was made from their blood. Serums to fight with diphtheria and tetanus were developed this way. It can be inferred from the passage that horses were

  1. given immunity to diseases

  2. generally quite immune to diseases

  3. given medicines to fight toxins

  4. given diphtheria and tetanus serums
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Option 2 files the sentense, as they built up immunities which helped humans create serums from their blood.

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