Art historian: This painting, purportedly by Mary Cassatt, is a forgery. Although the canvas and other materials are consistent with most of Cassatt' s work, and the subject matter is similar to that of Cassatt' s finest paintings, the brush style of this painting is not found in any work known to be Cassatt' s. Hence this painting is definitely not a genuine Cassatt. The art historian's argument depends on assuming which one of the following? ["No painter other than Cassatt would be able to match Cassatt's brush style perfectly.", "None of Cassatt's works is painted using a brush style that is not exhibited in any of her known works.", "The most characteristic feature of Cassatt's work is her brush style.", "Cassatt's work generally had a characteristic subject matter that distinguished it from the work of other painters of her era."]