Find the inverse Laplace transform of f(s) = 2s / [s(s-1)(s-3)]:

a. eᵗ - 3e³ᵗ
b. eᵗ + 3e³ᵗ
c. e^(-t) - 3e⁻³ᵗ
d. e^(-t) + 3e⁻³ᵗ