Final answer:
a. Mindfulness. The cognitive skill of learning to tolerate uncertain and unfamiliar experiences is best described as mindfulness.
Step-by-step explanation:
The cognitive skill of learning to tolerate uncertain and unfamiliar experiences is best described as mindfulness. Mindfulness is the practice of paying attention to the present moment without judgment and with an attitude of openness and curiosity. It involves being aware of one's thoughts, feelings, sensations, and surroundings. Through mindfulness, individuals develop the ability to stay calm and centered in the face of uncertainty or unfamiliarity.