Anaerobic respiration occurs when
water levels are low
light intensity is low
ph is unbalanced
oxygen is not present

oxygen is not present is correct option.

Explanation:

Anaerobic respiration occurs in the absence of Oxygen, it uses organic or inorganic molecules as electron acceptors.In anaerobic respiration, there is a breakdown glucose molecule in the absence of oxygen. In this process, lactic acid is producedDuring the intense exercise supply of oxygen is less when oxygen is less, in that case, muscle cell performs anaerobic respiration and then pyruvate is converted into lactic acid.

Ribonuclease activity is a type of nuclease that catalyzes the degradation of rna into small components.

The correct answer is d