Praising a historian for factual accuracy in describing events is like praising an architect for using well-seasoned timber or properly mixed concrete in a building.
Inferences:
Like an architect's ability to design a house is based on his theoretical knowledge as well as the creativity that he brings to the table.
Seasoned Timber or properly mixed concrete is important but that is the subset of Architect, which is the basics to be accounted for. It is the basics of being an Architect.
His ability to design the house is not on concrete mixing, as it is the same and minimum requirement for every architect.

The author of this statement is arguing that

(A) non historians can appreciate well-written historical accounts, but they cannot judge the accuracy of a historian's version of events

Wrong. The argument states the opposite. The minimum requirement for historians is to remember the historical events accurately.

(B) history is analogous to architecture in that both disciplines build on foundations laid by other professions

Wrong. Botht the professions are compared in terms of the basic and minimum knowledge required to take upon that profession. No foundations or disciplines are the same for both the profession. Historians could have been compared to another profession like Doctor and still this analogy will stand true.

(C) a good historian must have a thorough knowledge of auxiliary sciences that help establish facts about events

Wrong. This is cross computing the statements from one profession to another. These are two different professions and hence should not be mixed.

(D) the credibility of a historian's argument depends on the amount of information the historian has available

Wrong. This is exactly opposite of what the argument is saying. Historical information is the minimum requirement required from the historians and in no way affects the credibility of Historians.

(E) a historian has an obligation to be factually accurate, but accuracy is not the historian's most notable accomplishment

True. They are obligated or this is a minimum requirement. This is not something out of the world phenomena.