Final answer:
RNA polymerase is considered a housekeeping protein because it is an enzyme required for the fundamental process of transcribing RNA from DNA, which is essential for cell function.
Step-by-step explanation:
The student has asked which of the following is considered a housekeeping protein: RNA polymerase, insulin, hemoglobin, an antibody, or cortisol. Among the options provided, RNA polymerase is considered a housekeeping protein. Housekeeping proteins are those required for the basic functions of the cell, such as enzymes involved in the central processes of DNA replication, RNA transcription, and metabolism.
RNA polymerase is an enzyme responsible for synthesizing RNA from a DNA template, a fundamental process occurring in all cells, thus making it a housekeeping protein. Other options, such as insulin and cortisol, are hormones; hemoglobin is involved in oxygen transport in the blood; and an antibody is a component of the adaptive immune system.