Which of these is NOT a factor that may lead to different conclusions from two different studies investigating the same thing (eg., the relationship, if any, between caffeinated coffee and memory)?

a. different amounts of caffeine
b. different sample sizes using a control group
c. different ways of evaluating memory (eg., long-term vs. short-term memory)
d. different types of participants (eg., participants of different ages or professions)
e. using a control group

option d:using a control group

Explanation:

every experiment always have a contro group. it  is the population or group in a study that does not have the item to be tested that it is does not receive the exeprimental treatment. it used for comparison or a reference point so as to know or ascertain the result gotten from the rest groups. it helps to minimize error and it increases the precision of an experiment. the control group narrow your attention only to that thing you are trying to test. control group do not provide two different result. as a check, it provides only one result. it is either a positive control result or a negative control result.

the answer is a. now keep my answer here.

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