If a risk has a 20 percent chance of happening in a given month, and the project is expected to last five months, what is the probability that this risk event will occur during the fourth month of the

Less than 1% would imply the probability decreases over time, which is incorrect for an independent monthly probability.

Each month is an independent time period, so the 20% probability of occurrence applies to any given month in isolation, including the fourth month. The probability does not accumulate across prior months unless the question asks for cumulative probability; since it asks about the fourth month specifically, the answer is simply 20%.

60% would represent an approximate cumulative probability over three months using complement math, not the probability for a single specific month.

80% would suggest a cumulative probability over four months, which is not what the question asks - it asks about the fourth month in isolation.