Answer: B) A planned unit development
Explanation: The planned development of the unit is a planned and purposeful use of land and space where densely populated residential units are being built with all the necessary amenities and features. It is also a regulatory process for the use of space and land, as it regulates the optimal use of the said space and land for different purposes, from housing, shopping malls, parks, children's playgrounds, sports and spa centres, etc. Such blocks of flats and all the aforementioned dedicated contents are also cost-effective, since the use of that space and land on which densely populated residential units will be erected and will generate good income is optimised.