Critical Reasoning

Reviewer: The book Art’s Decline argues that European painters today lack skills that were common among European painters of preceding centuries. In this the book must be right, since its analysis of 100 paintings, 50 old and 50 contemporary, demonstrates convincingly that none of the contemporary paintings are executed as skillfully as the older paintings.
Which of the following points to the most serious logical flaw in the reviewer's argument?
(A) The paintings chosen by the book's author for analysis could be those that most support the book's thesis.
(B) There could be criteria other than the technical skill of the artist by which to evaluate a painting.
(C) The title of the book could cause readers to accept the book's thesis even before they read the analysis of the paintings that supports it.
(D) The particular methods currently used by European painters could require less artistic skill than do methods used by painters in other parts of the world.
(E) A reader who was not familiar with the language of art criticism might not be convinced by the book's analysis of the 100 paintings.

OA is A

Please explain.