Agar-agar is produced from—

✅Explanation
-Agar-agar is a gelatinous substance derived from the cell walls of certain species of red algae, primarily from the genus Gelidium. It is widely used as a solidifying agent in microbiological culture media, food products, and various other applications due to its unique gelling properties.

📌Other Options Explanations:
-Option A: Nostoc – Nostoc is a genus of cyanobacteria (blue-green algae) that can fix atmospheric nitrogen. While some cyanobacteria produce extracellular polysaccharides, they are not the source of agar-agar.
-Option B: Yeast – Yeasts are unicellular fungi used in various food and industrial processes but do not produce agar-agar.
-Option C: Oscillatoria – Another genus of cyanobacteria, but like Nostoc, they do not produce agar-agar.