Final answer:
The cost of living in an incorrect group is 'increased probability of being singled out by a predator' since group living often provides 'safety in numbers,' reducing individual predation risks.
Step-by-step explanation:
The question refers to the costs or disadvantages of living in a group from a biological perspective. Living in groups can indeed have several drawbacks. One is increased competition for food, as more individuals must share the same resources. Another is the increased probability of catching a disease because pathogens can spread more easily through densely populated communities. Also, there is increased competition for mates, with more individuals vying for reproductive opportunities. However, one option that is not a cost of living in a group is an 'increased probability of being singled out by a predator'. This is because group living often dilutes an individual's risk of predation through the 'safety in numbers' effect - a large group can confuse or deter predators, making it more difficult for predators to single out one individual.