Anchor the answer in the Alma-Ata list of 1978, which spells out eight building blocks of primary health care. They cover health education, control of locally common diseases, immunization, maternal and child health with family planning, supply of essential drugs, nutrition, treatment of common ailments and injuries, and clean water with sanitation.
Now scan the choices. Supplying essential drugs sits squarely on that list. Immunizing against major infections is on it too. Health education actually heads the list. Each of these is therefore a genuine component.
Cost effectiveness is a different kind of idea. It describes a quality we want services to have, not a defined element of the package. Because it is not one of the eight named components, it is the statement that does not belong.
\[\boxed{\text{Cost effectiveness}}\]