Answer: A. As one population increases, the other population also increases.
A boom period is best described when a general rapid population growth occurs. As this phenomenon is general and the question does not provide additional information about the presence of the species inter-dependency, both populations will increase. However, this is part of a cycle known and the "boom and bust" population growth cycle. According to the rule, this rapid growth period is followed by a bust period in which the population falls back to its minimal level. A good example of this is the plankton bloom.
