PLEASE HELP😌😌

If 100. mL of 18.0 M H2SO4 is diluted by adding water to a volume of 600. mL, what is the molarity of the diluted solution of H2SO4?
a. 3.00 M
b. 3.33 M
c. 180 M
d. 0.180 M

the amount (moles) of H2SO4 is constant

... but the volume increases by 6 times

molarity is 1/6th of the original