In how many cities did Maharaja Jai Singh II build Jantar Mantar?

 a) Four
 b) Two
 c) Three
 d) Five

RRB NTPC-2017

Five. In the early 18th century, Maharaja Jai Singh II of Jaipur constructed five Jantar Mantars in total, in New Delhi, Jaipur, Ujjain, Mathura and Varanasi,