Critical Reasoning

The traditional treatment of strep infections has been a seven-day course of antibiotics, either penicillin or erythromycin. However, since many patients stop taking those drugs within three days, reinfection is common in cases where those drugs are prescribed. A new antibiotic requires only a three-day course of treatment. Therefore, reinfection will probably be less common in cases where the new antibiotic is prescribed than in cases where either penicillin or erythromycin is prescribed.
Which of the following, if true, most strengthens the argument?

A. Some of the people who are allergic to penicillin are likely to be allergic to the new antibiotic.
B. A course of treatment with the new antibiotic costs about the same as a course of treatment with either penicillin or erythromycin.
C. The new antibiotic has been shown to be effective in eradicating bacterial infections other than strep.
D. Some physicians have already begun to prescribe the new antibiotic instead of penicillin or erythromycin for the treatment of some strep infections.
E. Regardless of whether they take a traditional antibiotic or the new one, most patients feel fully recovered after taking the drug for three days.
qa is e.

What's the best approach to determine the answer? why is option E and A out of the contest in choosing the right answer?

Statement C also strengthens the argument.

How can I know which one (C or E) most strengthens the argument?

Experts, I would appreciate some help.

A tricky one.

The conclusion: Reinfection will probably be less common in cases where the new antibiotic is prescribed than in cases where either penicillin or erythromycin is prescribed.

The evidence: A new antibiotic requires only a three-day course of treatment. The old one antibiotics requires a seven-day course, but many people stop within 3 days.

We need to strengthen the conclusion, so we need to show that the new treatment is more effective in preventing reinfection in actual practice. It other words, it doesn't matter which antibiotic is "better." The problem with the old treatment is that people stop taking it too soon. Why? Well Choice E gives us a reason: They feel better after only 3 days. Furthermore, Choice E says that they also feel better after only 3 days on the new stuff, but that's okay, because the treatment has run its course.

You're a doctor. You know that with the new stuff, people won't feel better until the treatment has run its course. They're now safe from reinfection. With the old stuff, they will feel better before that has happened. They're not safe. If you, the doctor, choose to use the new stuff, then you agree that Choice E has strengthened the conclusion.

Let me know if you've still got questions.

Regarding Choice C -- as soon as you see that word "other," alarms should go off. Who gives a hoot about other infections? This argument is about strep reinfections.

Thank you so mucho Economist.