Thanks for asking the question.
Explanation:
1 atm= 10.1m of water
=760mm of Hg
=1013milibar
=1.013kgf\cm^2
=0.1013N\mm^2(MPa)
So, option A is considered the right one
1milibar= 1\1013atm
1mm of Hg=1\760atm
1N\mm^2=1\0.1013atm
1kgf\cm^2=1\1.013atm
Hope it helps.
