The correct options are
B Mumbai has a larger population density compared to Bangalore
D Real estate prices in Mumbai are higher compared to Bangalore.
For a same area of land, a taller building would be able to accomodate a larger number of people compared to a less tall buidling. Hence, taller buildings results in more efficient land use. This is required because for the same land area, there are more people in Mumbai compared to Bangalore i.e., Mumbai has a larger population density. The higher demand for land results in hugher real estate prices in Mumbai. Both cities have access to the same technology.