From Her Review of Research on Attentional Processes in Skill-Learning

From her review of research on attentional processes in skill-learning, Wulf (2007)
Concluded that:

A) An internal focus of attention is more effective than an external one
B) Attentional focus is irrelevant to skill-learning
C) An external focus of attention is more effective than an internal one
D) The idea of attentional focus is a myth