Organisms associated with the first and third trophic levels include macrophytes, phytoplankton, chemoautotrophs, and insectivorous plants. However, the correct answer is option 'D', which refers to insectivorous plants. Let's explain why this is the correct answer in detail:

Insectivorous plants:
- Insectivorous plants are a group of plants that have adapted to obtain nutrients, particularly nitrogen, from capturing and digesting insects. They have evolved various mechanisms to attract, trap, and digest their prey.
- These plants primarily grow in nutrient-poor environments such as bogs, swamps, and other wetlands where the availability of nitrogen is limited. By capturing and digesting insects, they supplement their nutrient requirements.
- The insects trapped by insectivorous plants are typically small invertebrates like flies, mosquitoes, ants, and beetles. These plants use various trapping mechanisms such as sticky hairs, pitcher-shaped leaves, snap traps, and suction traps to capture their prey.
- Once the insects are trapped, the plants secrete digestive enzymes to break down the prey and absorb the released nutrients, including nitrogen.
- By consuming insects, insectivorous plants play an important role in the ecosystem by controlling insect populations and recycling nutrients.
- Some well-known examples of insectivorous plants include Venus flytrap (Dionaea muscipula), pitcher plants (Sarracenia spp.), sundews (Drosera spp.), and bladderworts (Utricularia spp.).

Other options:
- Macrophytes: These are large aquatic plants that grow in freshwater or marine environments. They play a crucial role in the ecosystem by providing habitats, food, and oxygen for other organisms. However, they are primarily associated with the second trophic level as producers.
- Phytoplankton: These are microscopic photosynthetic organisms that float in water bodies and form the basis of aquatic food chains. They are primary producers and occupy the first trophic level.
- Chemoautotrophs: These are organisms, such as certain bacteria and archaea, that obtain energy from inorganic chemical reactions rather than sunlight. They are associated with deep-sea hydrothermal vents and other extreme environments. While they are important for ecosystem functioning, they are not directly associated with the first or third trophic levels.