44. Carrying capacity is
(A) seldom reached by marine producers and consumers because of the vast resources of the ocean.
(B) the maximum population size that a particular environment can support.
(C) fixed for most species over most of their range most of the time.
(D) determined by density and dispersion data.
(E) the term used to describe the stress a population undergoes due to limited resources.

The correct answer is **(B) the maximum population size that a particular environment can support.**

### Explanation:
**Carrying capacity** refers to the maximum population size of a species that an environment can support without degrading the environment. It is determined by the availability of resources such as food, space, and water, as well as factors like predation, disease, and competition.

Here’s why the other options are incorrect:

- **(A) Seldom reached by marine producers and consumers because of the vast resources of the ocean**: While the ocean may have vast resources, carrying capacity can still be reached in marine ecosystems, especially when environmental stressors (overfishing, pollution) come into play.

- **(C) Fixed for most species over most of their range most of the time**: Carrying capacity is not fixed; it can change based on environmental conditions, availability of resources, and species interactions.

- **(D) Determined by density and dispersion data**: Density and dispersion data can provide information about how a population is distributed, but carrying capacity is influenced by resource availability and environmental factors, not just density and dispersion.

- **(E) The term used to describe the stress a population undergoes due to limited resources**: This statement is more related to the concept of **population stress** or **overcrowding**, not the definition of carrying capacity itself.

Thus, **(B)** is the most accurate definition of carrying capacity.