The three characteristics of marginal groups in London are as follows.
(i) Most of the poor people were criminals who lived by stealing.
(ii) A large number of women worked in factories in the late 18th and 19th centuries.
(iii) A large number of children were pushed into low paid work within the households. The passage talks of outbreak of dengue during the past 15 years. This contradicts the fact given in the question.