The correct option is A Producers
Ponds and lakes are stationary freshwater ecosystems. Ponds and lakes are characterised by a maximum number of producers. Producers include phytoplanktons (e.g.,diatoms, desmids, Chlorella, Chlamydomonas, Spirogyra, Oedogonium, Zygonema), as they are able to produce their own food. Thus, the correct answer is option A.