The correct answer is B) Erickson.
It was Erick Erickson who asserted that children must be given the opportunity to explore and work on different materials so that they will develop a sense of initiative instead of guilt.
We are referring to the third stage of the theory elaborated by Erick Erickson called "Psychosocial Development." It encompasses children from 3 to 5 years old that are in the preschool period. The stage is the "Initiative vs. Guilt," where children start to declare their control and power over things using direct action and social interplay.
The other options of the question were A) Kohlberg, C) Maslow, and D) Gardner.