Which of the following is not a condition for a random variable to follow a Poisson process?
1) The number of events in non-overlapping intervals are independent.
2) The probability of more than one event occurring in an infinitesimally small interval is zero.
3) The probability of an event occurring in a small interval is proportional to the length of the interval.
4) The number of events in a given interval follows a Poisson distribution.