A function that does not return anything has return type

Idon understand these and need some ! ?

Which demographic challenge is europe currently experiencing? a. an aging and decreasing population b. a baby boomc. an unequal distribution between males and females d. a large group of teenagers moving through the school system(i chose a but i'm unsure)

Technician a says engine assemblies can be mounted longitudinally in a chassis. technician b says engine assemblies can be mounted transversely in a chassis. who is correct?