I am not a fundamental analyst, I had a rough understanding on what this comparison was, until watching some videos recently gave me conflicting views, so forgive me if this question sounds stupid.

With respect to the quarter ending, March,2021, What exactly do stock analysts mean when they say Quarter on Quarter?.

Is that a comparison between 

1) Jan, Feb, March of 2021 and Oct, Nov, Dec of 2020.

2) Jan, Feb, March, of 2021 and Jan, Feb, March 2020.

3) The whole 12 months from Apr 2020 to March 2021 and Apr 1999 to March 2020.

@Gopal Kavalireddi  please help me out here. Thanks