The construction of a sewer system in victorian london was made possible by?

The construction of sewer system in Victoria London was made possible by  a better understanding of disease (caused by poor sanitation), good engineering skills in regard to waste disposal and a government that was willing to do everything to solve the problem of poor sanitation.

Construction of the London sewerage system began in 1859, led by a young engineer called Joseph Bazalgette. It was completed in 1865  and it spanned an incredible 450 miles. Pumping mills were used at various points to keep things flowing in the right direction. It was a huge success and London became a healthier, cleaner city.

answer; i believe that the correct answer is (tobacco);

its c not d   tell me if that´s correct