Which of the Following Is an Example of Explicit Knowledge

Which of the following is an example of explicit knowledge?

A) Juan learned to drive a car at the age of 16,and now he is a professional racer.
B) Shiera started playing the piano at the age of 7,and now she is a professional pianist.
C) Jordan,an executive chef in a five-star restaurant,uses a secret recipe book owned by the restaurant to prepare exotic dishes.
D) Tomm,a doctor,diagnoses a rare illness and prescribes a course of action to cure it.