Correct Option: B. Introduction of a new predator Detailed Explanation: Carrying Capacity Defined: Carrying capacity refers to the maximum number of individuals of a particular species that an environment can sustainably support over time. This capacity is influenced by various biotic (living) and abiotic (non-living) factors, including food availability, habitat conditions, competition, and predation. Why Option B is Correct: 1. Introduction of a New Predator: - When a new predator is introduced into an ecosystem, it can significantly impact the population of prey species. Predators directly reduce the number of individuals in the prey population by consuming them. - This predation pressure can lead to a decline in the prey population, which in turn can decrease the overall carrying capacity of that species in the ecosystem. If the prey population decreases, there are fewer individuals to reproduce, leading to a potential population crash. - For example, if a new predator is introduced to an area where a specific herbivore species lives, the herbivore population may decline due to increased predation. This decline can lead to less herbivory pressure on plants, but it can also disrupt the entire food web, affecting other species that rely on the herbivore for food. Why the Other Options are Incorrect or Weaker: A. Increased availability of food resources: - Increased food availability typically leads to an increase in the carrying capacity of a population. More food means that more individuals can survive and reproduce, which supports a larger population. Therefore, this option would not cause a decrease in carrying capacity. C. Improved habitat conditions: - Improved habitat conditions, such as better shelter, water availability, and suitable breeding sites, generally enhance the carrying capacity of an ecosystem. When conditions are favorable, populations can thrive and grow, leading to an increase in carrying capacity rather than a decrease. D. Decreased competition for resources: - Decreased competition for resources occurs when there are fewer individuals competing for the same resources (like food, water, or space). This situation often leads to an increase in the carrying capacity because individuals can access the resources they need more easily, allowing for population growth. Thus, this option would not lead to a decrease in carrying capacity. Summary of Key Points:

• Carrying Capacity: The maximum sustainable population size in an ecosystem.
• Impact of Predators: Introduction of a new predator can decrease prey populations, leading to a lower carrying capacity.
• Food and Habitat: Increased food and improved habitat conditions enhance carrying capacity.
• Competition: Decreased competition allows for population growth, increasing carrying capacity.

By understanding these concepts, students can better grasp how different factors influence population dynamics and ecosystem health.