People who get an influenza vaccine produce antibodies that protect them against being infected by the particular influenza viruses that are used in the vaccine. Which of the following explains why an influenza vaccine might be ineffective?
OA.
The antibodies that were developed in response to the vaccine are gradually flushed from the person's immune system.
OB. The DNA of the person who was vaccinated
undergoes random genetic changes that can result in the antibodies being
destroyed, so the immune system does not recognize the viruses.
OC. The antibodies that were developed in response to the vaccine change shape and no longer recognize subsequent
generations of the viruses.
OD
Viruses undergo random genetic changes that can result in antibodies no longer recognizing some individual viruses,
and this resistance can be passed to subsequent generations
no

  like australopithecus afarensis; probably the direct ancestor of this group. africa: 5.8 to 4.4 million years ago. 

In order to understand the problems of unwanted infertility in a country — the gambia — where the desire for children and the fertility is very high, a population-based survey was undertaken. all infertile women in 24 randomly selected enumeration areas were assessed. the study included a review of the problems faced and coping mechanisms employed by infertility clients and types of health care available for infertile couples in the different types and levels of the formal and traditional health system. half of the infertile couples failed to seek formal health care, and they have to reach a certain level of care in order to be properly managed. alternative care is often sought. child fostering is also a frequent solution to childlessness. in-depth interviews revealed that traditional care like healers and spiritual leaders are frequently consulted long before formal health care. this delay could be a problem in those cases where infertility is caused by infections.