Caleb and Brianna play tennis together often, and Caleb has begun to be concerned about Brianna’s form. He believes that if she worked on her form, she could be faster and more controlled on court with less effort. Which is the MOST useful feedback Caleb could give Brianna?

a
“You aren’t as fast and controlled as you should be.”

b
“Just watch me a minute to see what you’re not doing right.”

c
“Your effort is strong, but you waste a lot of it.”

d
“I can help you have better speed and control.”