Final answer:
The marketing concept emerged in the mid-1950s as a customer-centered philosophy focused on meeting customer needs. It signifies a shift from production or selling-oriented strategies to value creation for customers.
Step-by-step explanation:
The concept that emerged in the mid-1950s as a customer-centered, sense-and-respond philosophy is D) the marketing concept. This approach represents a shift away from the previous focus on production and selling towards a greater emphasis on understanding and meeting the needs and wants of customers. The marketing concept advocates for businesses to create value for customers in order to capture value from them in return.