​The units of molar extinction coefficient are:​

Correct option is A

Explanation-

The molar extinction coefficient (also called molar absorptivity, denoted by ε) is a constant that relates how strongly a chemical species absorbs light at a given wavelength.

It appears in Beer-Lambert Law:

$$A = \varepsilon \cdot c \cdot l$$

Where:
= Absorbance (unitless)
 = Molar extinction coefficient
  = Concentration of the solution (mol/L)
 = Path length of the cuvette (cm)

Rearranging the equation:
                                $$\varepsilon = \frac{A}{c \cdot l}$$​​
​Since:
Absorbance (A) has no units,
Concentration (c) has units mol/L,
Path length (l) has units cm,
Substitute the units into the formula:

                                           $$\varepsilon = \frac{1}{\text{mol/L} \cdot \text{cm}} = \frac{L}{\text{mol} \cdot \text{cm}}$$ = L mol⁻¹ cm⁻¹

L: Liters — unit of volume
mol⁻¹: Per mole — unit of amount of substance
cm⁻¹: Per centimeter — unit of path length
This unit tells you how much light is absorbed per mole of substance in 1 liter solution over a 1 cm path length.

Final answer - option a : L mol⁻¹ cm⁻¹