New National Security Adviser to the US President

Question: Who amongst the following has recently been appointed the new National Security Adviser to the US President?
(a) John R. Bolton
(b) Mike Popeo
(c) Le. General H.R. McMaster
(d) Gary Cohen
Answer: (a) 
Related Facts: 

  • On March 23rd, 2018, Jhon R. Bolton appointed US President Donald Trump’s new national security adviser.
  • His tenure will begin on April 9th, 2018.
  • At this post he will replace new National Security Adviser to the US President.
  • Bolton was a permanent representative of the United States in the year 2005-06.

Reference:
http://www.bbc.com/news/world-us-canada-43509695
https://edition.cnn.com/2018/03/22/politics/trump-replace-national-security-adviser-mcmaster-bolton/index.html
http://time.com/5211928/hr-mcmaster-resign-john-bolton-trump-white-house-national-security-advisor/