When developing an experimental design, which action would improve the quality of the results?
A. Ensure that it answers a question about cause and effect.
B. Include as many responding variables as possible.
C. Keep the sample size of test subjects to a minimum.
O
D. Have a different researcher make the measurements.

Abaseball is thrown from the outfield toward the catcher. when the ball reaches its highest point, which statement is true? (a)its velocity is not zero, but its acceleration is zero. (b) its velocity and its acceleration are both zero. (c) its velocity is perpendicular to its acceleration. (d) its acceleration depends on the angle at which the ball was thrown. (e) none of the above statements are true.