A recent survey revealed that the proportion of stage artists belongin

A recent survey revealed that the proportion of stage artists belonging to Theatreville that visited skin specialists for treatment related to skin lesions has increased significantly over the past ten years. As a part of their jobs, stage artists typically use make-up containing lead, the main culprit behind such skin lesions. Therefore, either the artists are using unusually higher amount of make-up or they have more sensitive skins than the artists had a decade ago.

Which of the following is an assumption on which the argument depends?

A) There has not been any significant increase in the number of stage artists in Theatreville. - Significant increase in Number of artist does not mean that visits to specialist for skin lesions will increase. Increased staff might /might not be using makeup.
B) The make-up kits that most artists have been using now do not achieve long-lasting make-up effects by significantly increasing the concentration of lead. - if We negate this argument it would mean that increased visits are due to increase in concentration of lead. Conclusion of author that increased visits are because of higher amount of make up used or increased sensitivity will simply fall apart.
C) No other ingredient in the make-up used by the stage artists is responsible for other skin irritations for which a visit to the doctor is required. - Irrelevant. Increased visits are related to skin lesions.
D) People with highly sensitive skins are likely to be vulnerable to the side effects of lead used in the make-up. - Irrelevent
E) Some companies have introduced high quality make-up in which the composition does not require the inclusion of high quantities of lead-based substances. - Out of scope

Hope it helps !!