Which of the following is among the criticisms of Vygotsky's theory?
a) Vygotsky was specific about age-related changes and generalized all individuals.
b) Vygotsky overemphasized the role of individual development over social interaction.
c) Vygotsky's theory lacks empirical evidence to support its claims.
d) Vygotsky's cultural-historical approach neglects the role of biology in development.