Which of the following statements is (are) true?
a. a combination of physical and mental practice is better than physical practice alone, given the same time frame.
b. mental practice can be employed as a substitute for physical practice if an athlete is injured.
c. mental practice should be used as a supplement to physical practice rather than as a replacement for physical practice.
d. a and b
e. b and c

C. Mental practice should be used as a supplement to physical practice rather than as a replacement for physical practice.

hello,

answer: a federal government has final authority on interstate/inter provincial  and international affairs, a confederation is one where the central/national government or authority is governing body what does not have final say over the same matters. hopefully this and i will try again if you don't like this answer : )

best of luck!

answer; does not include a reference to the audience;