In a normal distribution:
a. most scores will occur in the high range.
b. most scores will occur in the low range.
c. most scores will fall in the middle range.
d. scores will be evenly spread across the entire range.

c. most scores will fall in the middle range.

Explanation:

The mode of a set of data values is the value that appears most often.  If you think about how the normal distribution looks like. The highest point of the bell will be the Mode. In a symmetric normal distribution , the mode will be in the middle.

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.        

where is the