Bacille Calmette-Guérin (BCG) is a vaccine for tuberculosis (TB) disease. This vaccine is not widely used in the United States, but it is often given to infants and small children in other countries where TB is common. BCG does not always protect people from getting TB.
D. <span>controlled
is the right answer because a</span><span>n </span>experiment<span> in which an observer tests a hypothesis by looking for changes carried by alterations to a variable.</span>
They are oxygen, carbon, hydrogen, and nitrogen.
Answer:
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Explanation: