Consider the following kinds of organisms:<br/>1. Copepods<br/>2. Cyanobacteria<br/>3. Diatoms<br/>4. Foraminifera<br/><br/>Which of the above are primary producers in the food chains of oceans?

1. Copepods – These are small crustacean zooplankton, generally consumers, not primary producers. Verdict: Incorrect.

2. Cyanobacteria – They are photosynthetic microorganisms and form an important part of marine phytoplankton, hence primary producers. Verdict: Correct.

3. Diatoms – These are photosynthetic algae and among the most important primary producers in oceans. Verdict: Correct.

4. Foraminifera – These are mostly heterotrophic protists in marine environments, not primary producers. Verdict: Incorrect.

Therefore, the correct pair is 2 and 3.