Option 1 is the correct sequence of a food chain: Diatoms -> Crustaceans -> Herring.

A food chain represents the flow of energy and nutrients in an ecosystem. It starts with producers, which are usually plants or algae that can convert sunlight into energy through photosynthesis. Diatoms are microscopic algae and are considered primary producers in aquatic ecosystems. They absorb nutrients and use sunlight to produce organic compounds.

The next step in the food chain is the primary consumers, also known as herbivores, which feed directly on the producers. In this case, the primary consumer is crustaceans. Crustaceans are a group of animals that include shrimp, crabs, and lobsters. They feed on diatoms as their source of energy.

Finally, we have the secondary consumers, which are carnivores that feed on the primary consumers. Herring is a type of fish that feeds on crustaceans, making it the secondary consumer in this food chain.

In summary, the correct sequence is Diatoms -> Crustaceans -> Herring, representing the flow of energy and nutrients from producers to primary consumers to secondary consumers in the food chain.