GMAT Sentence Correction (SC) | Re: SV Agreement Revision: Every workday at dawn, the patriarch

There are three cases involve in this question :
1. Comparisons : We use superlative "richest" instead of "richer" to compare among five elements > eliminate D, E
2. S&V agreement : The patriarch is singular subject, it must be followed by singular verb such "leaves" > eliminate B
3. Parallelism : singular verb "leaves" must be parallel to another singular verb, hence "walks" is the correct one > eliminate C

So, A is the answer.

Note:
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