An experiment wants to determine the impact of caffeine on attention span.Which of the following best represents random assignment?



a. Selecting who will participate in the study without any specific pattern
b. Observing the level of attention exhibited by participants given caffeine
c. Placing participants into either the caffeine or non-caffeine group without any set pattern
d. Selecting those who drink caffeine regularly and have built a tolerance to the effects
e. Offering different levels of caffeine to the participants.