The question is incomplete as it does not have the option which are:
A- Change the position of the mask and then look for chest movement.
B- Blow into the mask more forcefully and then look for the chest to rise.
C- Re-tilt the victim's head and then attempt another ventilation.
D- Give 5 back blows and then check the victim's mouth.
Answer:
C- Re-tilt the victim's head and then attempt another ventilation.
Explanation:
Cardiopulmonary resuscitation is a set of procedure which is performed on the person when the person faints or the person is unable to breathe.
The CPR is provided immediately as due to the blockage of the vessels enough oxygen does not reach to the brain and other parts and they die out.
In the given condition, if ventilation is provided to the patient and chest does not rise then the person should again try to provide ventilation to the person by tilting the head of the victim. This will allow the person to breathe and chances are that blockage will reopen.
Thus, Option-C is correct.