Mina is probably diagnosed and suffers from the disorder of seasonal affective disorder which is letter c in the choices above. It is because a person with seasonal affective disorder is usually treated and undergoes to light therapy and takes antidepressant in which Mina has been given by her doctor.
Answer:
A control should have been included in the investigation
Explanation:
It is impossible for the student to interpret a correct conclusion about his experiment, without adding a control treatment where he can really compare the differences between the variables.
Control treatment is an element of research that receives all factors, except the variable being tested. The control serves to make comparisons with the other treatments, allowing to observe the exact difference between a system where the variable was tested and the system where it was not.
In the case of the question above, it would have been necessary for the student to have placed a cart on a ramp of normal height and without sandpaper. That way he could compare the speed between this cart and the carts on the other ramps, thus having a correct result.
<span>A barter system is an old method of exchange. Th is system has been used for centuries and long before money was invented. People exchanged services and goods for other services and goods in return. ... The value of bartering items can be negotiated with the other party.</span>
The answer to your question is b
