Geography can affect culture in all of the following ways except
a.
available resources
c.
population shifts
b.
genetic composition
d.
diet

Taking into consideration that geography is the study of earth, its characteristics, its atmosphere and its interaction with living beings, we can conclude that the only aspect among the available options that is not related to this science is genetic composition. Geography affects a culture's diet because it partially depends on what can grow in the region. It also affects available resources because of the physical characteristics and atmosphere it may offer on a certain area over another. In the same way, it determines population shifts as people often are moved to migrate seeking a more favorable geographical setting.

Therefore, your best answer is option is genetic composition.