The main point of the cartoon "The Genii of Intolerance," with the caption "A dangerous ally for the cause of women's suffrage," suggests that there is a negative association between the women's suffrage movement and the cause of Prohibition. The phrase "dangerous ally" implies that aligning with Prohibition could be harmful to the suffrage movement. Therefore, the correct answer is:
D. • Suffragists should not be linked to the cause of Prohibition.