Answer: a. decreases
Step-by-step explanation:
A population density can be define as the number of individuals in a population of a species living in a unit of area in a particular time. The population density can be influenced by number of births, deaths, immigration, emigration and competition. The number of live birth in a concerned population and immigration (introduction of the new members) are likely to increase the population density of a region. But the number of deaths and emigration (the members of the same population move to a new habitat), and the competition (the members of the same species may compete among themselves for the same resources, the superior one will receive the resources and the inferior one will loose and may die) will decrease the population density.
According to the given situation, death rate and competition among the individuals will likely to decrease the population density.