What were the steps taken to clean up London in the 19^th century?

In the 19th century London, different steps were taken to clean up the city which has faced large scale urbanization and migration.

a. the city was expanded to suburban areas to decongest the locality and provide the population with jobs.

b. The British government introduced a rent system to meet housing demands.

c. Planning was made to construct a planned garden city with green belts to provide people with work and housing and to maintain the ecology.

d. public and private places including industrial areas were cleaned.

e. large blocks of apartments were built for the people.