D. Trachea, is the answer.
Answer:
White blood cells are an important part of the immune system. HIV infects and destroys certain white blood cells called CD4+ cells. If too many CD4+ cells are destroyed, the body can no longer defend itself against infection. The last stage of HIV infection is AIDS (acquired immunodeficiency syndrome).
Explanation:
C. one complete turn on its axis.
It is important to do a warmup before exercise, because this ensures
that blood is being pumped around the body, and is preparing joints and
muscles for any strenuous activity that you are about to partake in.
Without a warm-up, these muscles and joints will not move as easily and
this could result in serious injury.