Final answer:
The OPTIMAL theory by Wulf and Lewthwaite outlines that focusing on external factors rather than oneself, along with strong motivation and attention, enhances the learning of motor skills.
Step-by-step explanation:
The OPTIMAL theory of motor learning by Wulf and Lewthwaite stresses the importance of external focus and motivational factors in learning motor skills effectively. The correct answer to the question is that motivational and attentional factors contribute to performance and learning by strengthening the coupling of goals to actions. Thus, choice b) of the provided options is incorrect, and choice a) is also incorrect because an increased focus on the self over the task at hand is detrimental to motor learning. Choice c) discusses setting low expectancies and facilitating an internal focus, which contradicts the concepts proposed by Wulf and Lewthwaite that promote an external focus for enhanced motor learning. Lastly, choice d) is untrue, as an increased focus on the task goal is actually beneficial and creates a positive cycle for motor learning, not a negative one.