Answer: D. During an economic downturn, a company changes its computer policy to only allow purchases of windows-based laptops and see profits go down. The company concludes that windows-based laptops cause profits to go down
Step-by-step explanation:
In the other options, the new activity done by the company were definite causes of the effects that followed. A more efficient production process will cause gains in productivity. Coupons will bring in more sales and paying employees more will encourage them to engage in more sales.
Concluding that a computer type causes profits to go down however in a period where the economy as a whole is buying less, is simply correlation. In an economic downturn, people are buying less goods in general. The laptops will be no exception and it is not a reflection of people's preference or lack thereof of them.