I need help with this question

The system of our body that helps fight infections even on getting exposed to disease-causing factors is our immune system. The cells responsible for this are mostly leucocytes, part of our defence system.
The outcome of lack of functioning of the immune system is it becomes prone to syndromes and diseases.It results in entrance of microbes in our body.Some disorders of immune system are :

1. HIV,AIDS,
2. Allergy,
3. Cancer of cells.

The two basic factors that parents should take care of for proper functioning of immune system in their children are:

1. Proper and sufficient nourishment for their children.
2. Parents should take the responsibility of providing vaccinations of different types of diseases to their children.