In the event that the nucleolus of a cell malfunctioned, the cell function that would be most impaired is d) protein synthesis.
The nucleolus is a dense region within the nucleus where ribosomal RNA (rRNA) is synthesized and combined with proteins to form ribosomal subunits. These ribosomal subunits are essential for assembling ribosomes, which are the cellular machinery responsible for translating messenger RNA (mRNA) into proteins. Therefore, if the nucleolus is not functioning properly, the production of ribosomes would be hindered, leading to a reduction in protein synthesis.
While other cellular functions like carbohydrate and lipid synthesis, ATP synthesis, and active transport involve various organelles and processes, the direct connection between the nucleolus and protein synthesis makes it the most impaired function when the nucleolus malfunctions.