Chris wants to build a birdhouse. He understands how to choose materials and measure them, but has never used woodworking tools. His father patiently demonstrates, then allows Chris to practice. When Chris cannot remember how to proceed in the process, his father demonstrates again, then guides Chris through the process. This demonstrates Vygotsky's concept of:

a. Cultural transmission
b. The zone of proximal development
c. Social interaction
d. Intergenerational transmission