Consider the following exponential probability density function. [ f(x) = (1/6)e⁽⁻ˣ/⁶⁾ for x ≥ 0 ]. If needed, round your answer to four decimal digits. (a) Choose the correct option for the integral of f(x) from 0 to infinity.
1) 1
2) 6
3) e
4) ⁰