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.

d concave shape of wave rock

explanation:

the concave shape of wave rock is a very good evidence that supports the evolution of earth due to chemical weathering. if we talk about structure of   wave rock, studies have estimated that it is around 2.7 billion years old. it also serves as the foundation of evidence that it was the place where australian continent began to form.

how the structure of wave rock was created?

studies suggest that structure of wave rock was created when the surrounded area was started to weather due to which deposition of material started on the part of land which now contains wave rock.

the structure of wave rock is considered to be one of the best-known landforms in australia. at the height of around 15 cm, there can be found flared slopes which formulate the margins of hyden rock. it is now assumed by geologists that wave rock was created by subsurface water-induced weathering and not by glaciers, waves or wind.

due to deposition of material over the period of long time, the wave rock became tougher and tougher due to weathering from surrounding terrain. this makes it a physical evidence that supports   the evolution of earth due to chemical weathering.

hope it !