Answer:
D = 3.81 x 10⁻² m = 3.81 cm
Step-by-step explanation:
We can use the formula of fringe spacing from Young's Double Slit experiment to answer this question:

where,
Δx = distance between two consecutive dark fringes
λ = wavelength of light beam = 5.37 x 10⁻⁷ m
L = Distance between screen and slits = 2.14 m
d = slit separation = 6.03 x 10⁻⁵ m
But, we need the distance between first dark fringe on 1 side to 2nd dark fringe on other side. It means we need twice the distance between two dark fringes:

where,
D = distance between first dark fringe on one side and 2nd dark fringe on other side of central maximum = ?
Therefore,

D = 3.81 x 10⁻² m = 3.81 cm