Answer : The correct option is, (3) 3.0 moles of HCl per liter of solution
Explanation :
Molarity : It is defined as the number of moles of solute present in one liter of the solution. The S.I unit of molarity is mole per liter.
It is represented as,

where,
V = volume of solution in liter
As we are given 3.0 M HCl(aq) solution this means that 3.0 moles of HCl present in one liter of solution.
Hence, a 3.0 M HCl(aq) solution contains a total of 3.0 moles of HCl per liter of solution.