Who was the first to use the word 'Megapolis' (Megalopolis)?

The word 'Denisovan' is sometimes mentioned in media in reference to

Which one of the following is the first urban settlement in the world to reach a population size of one million (million-plus city)?

Who is the propounder of the 'behavioural matrix'?

Who was the proponent of the concept of 'Lebensraum' (living space)?

Who among the following geographers is related to 'primate city' concept?