A National Institute of Health, Atlanta study shows that uncooked or improperly cooked pork consumption results in a severely infectious disease of the liver, caused by an organism called the tapeworm. In this study, 1,000 humans in an experimental group were given improperly cooked pork while a control group (consisting of 1,000 humans) was given perfectly cooked pork. Within a couple of weeks, around 80% of those who had consumed partially cooked pork showed symptoms of tapeworm infection. Thus, the study concluded that the infection must be due to the organism that does not get killed in case the pork is not properly cooked.
The above line of argument would be most greatly strengthened if it can be shown thatThe study observes many infections after undercooked pork and concludes the cause is a tapeworm organism that survives improper cooking. The argument is strongest if we add evidence that pork is a realistic transmission route for tapeworms, meaning the pork itself can carry the organism. This is the
key missing link.
A. nearly all the experimental group subjects who contracted the infection developed severe complications of the liver later
This is about how bad the illness became, not about why the infection happened. It does not strengthen the causal claim about undercooking.
B. the normal incidence of this disease among humans is just 0.01% in case of those eating pork
This shows the disease is usually rare, which helps a bit, but it does not directly connect the infection to pork carrying the organism or explain why undercooking matters.
C. those eating lighter quantities of improperly cooked pork develop more serious complications as compared to others who eat heavier quantities
This is about severity and has an odd dose pattern. It does not strengthen the claim that the infection is due to an organism surviving undercooking.
D. the tapeworm infection is rare among people and communities that are on a light, vegetarian diet much more than they are on pork and other meats
This is a broad correlation and still does not pin the infection on undercooked pork or on survival of the organism during cooking.
E. the tapeworm spends a great part of its overall lifecycle in the body of a pig, wherefrom it is transmitted to humans
This directly supports the needed mechanism: that the organism is actually present in pigs and can reach humans through pork, which makes the conclusion that undercooking lets it survive much more credible. It supports the idea that the pork is the carrier
from pig to human.
Answer: (E)