What is the SI unit of pressure ?
$
  (a){\text{ atmosphere}} \\
  (b){\text{ dyne/c}}{{\text{m}}^2} \\
  (c){\text{ pascal}} \\
  (d){\text{ mm of Hg}} \\
 $

Hint – In this question use the concept that the SI unit of force is Newton and the SI unit of area is ${m^2}$. Use the relation between pressure, force and area. To get the required SI unit as we know that that pressure is defined as force per unit area.

Complete step-by-step answer:
The SI unit of pressure is Pascal (represented as Pa) which is equal to one newton per square metre ($\dfrac{N}{m^2}$ or $\dfrac{kg}{ms^2}$). Interestingly, this name was given in 1971. Before that pressure in SI was measured in Newtons per square metre.
The other units of pressure are Bar, technical atmosphere (at), standard atmosphere (atm), Torr and pounds per square inch ($\dfrac{lbf}{in^2}$).
So the S.I unit of pressure is Pascal.
Hence option (C) is correct.

Note – SI units is known as international systems of units, it is a system of physical units based upon the meter, kilogram, second, ampere, kelvin, candela and mole together with a set of prefixes to indicate the multiplication or division by a power of 10.