They say a week in politics is a long time. Like politics, a week is a long time in teaching too!
This option is eliminated because of wrong comparison. Also, "as politics, a week" is certainly wrong. Eliminated
Your analysis is very good. However, the reason for eliminating Choice B - "As" - is not correct. When "As" is used for comparison, it MUST be followed by a clause. In this option, "As" is just followed by a anoun. "As" can ONLY be followed by anoun, when it presents role or function of someone/something. For example:
As a manager, John has made significant contributions in the company.
Here there is no comparison between "John" and "manager". Rtahre "john"himself is the "manager". His role in the company is of a manager.
Since Choice B in the given problem "As" is not followed by a clause, it now illogically presents the function of "a week" as "politics".
To learn the correct usages of "Like" and "As", click on the following link for a detailed article:as-vs-like-correct-and-incorrect-usages-133950.html
We have included in our course a special in-depth serries that features the correct usages of Like and As, why there is a confusion in the usage of "As" and how it can be resolved. There are three concepts files and an application file to practice the knowledge of the same. Log on to e-gmat
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Hope this helps.
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