A pond fills with organic matter during what?

A pond fills with organic matter when "pond ages from oligotrophic to mesotrophic".

Explanation:

The ponds are basically ranging from youngest to oldest in the given categories: Oligotrophic, Mesotrophic, or Eutrophic phases of live. The oligotrophic ponds are known as fresh or young waterbody. Oligotrophic bodies are low in nutrient quantities, like nitrogen and phosphorus, so donot encourage algae and aquatic plants productivity. The middle ages mesotrophic aquatic bodies are carrier of more nutrients and thus more readily the development of plants and algae take place than oligotrophics, but less than eutrophic production. As aging take place from oligotrophic to mesotrophic, the pond sides continue to slope less and the base of the pond starts to fill in with organic matter.

carbohydrates: (starches and sugars) composed of carbon, hydrogen, and oxygen.

lipids: (fats, oils, and waxes) are made of carbon and hydrogen atoms.

nucleic acids: contain hydrogen, oxygen, nitrogen, carbon, and phosphorus. they are polymers of nucleotides. a nucleotide has three parts, a 5-carbon sugar, a phosphate     (-po⬇️4) group, and a nitrogenous base.

proteins: made up of nitrogen, carbon, hydrogen, and oxygen. they are polymers of amino acids.

answer: the correct option is d. enzyme

lactase and carbonic anhydrase are the examples of enzymes.

lactase is an enzyme, which is present in the small intestine of mammals. it in the digestion of the disaccharide, lactose ( milk sugar) by converting it into two monosachharide, which are glucose and galactose.

carbonic anhydrase is present in the red blood cells. this enzyme plays significant role in the transport of co₂. it in the conversion of co₂ and h₂o into carbonic acid, which is then dissociated into bicarbonate ions and hydrogen ions.