Final answer:
The notion of gender differences in the 19th century was shaped by the Cult of Domesticity, which emphasized separate spheres for men and women. Therefore, the correct option is d.
Step-by-step explanation:
The notion of gender differences in the 19th century encompassed the Cult of Domesticity which emphasized separate spheres for men and women, with women being responsible for the home and family. This ideology defined women as the guardians of virtue and the spiritual heads of the home. Men, on the other hand, were seen as teachers of young boys and were considered to be in danger of slipping into savage ways of life without women's influence. Therefore, the correct answer is D. men were always in danger of slipping into some savage way of life, if not for women's influence.