Shiga toxin primarily affects cells by:

Shiga toxin is a potent virulence factor produced by certain bacteria, notably Shigella dysenteriae and some strains of Escherichia coli. Its mechanism of action is characterized by targeting the ribosomal machinery within host cells. The correct answer identifies that Shiga toxin inactivates the 60S ribosome, which is a critical component of the eukaryotic protein synthesis machinery.

By enzymatically modifying the rRNA component of the 60S ribosomal subunit, Shiga toxin disrupts protein synthesis. This leads to cellular stress and eventual death of the affected cells, especially in the intestinal epithelium where the toxin exerts its effects. The inhibition of protein synthesis resulting from the inactivation of the ribosome is a central feature of how Shiga toxin contributes to the pathogenesis of diseases like dysentery.

While other answers present plausible mechanisms, none accurately describe Shiga toxin's primary mode of action compared to its direct effect on the ribosomal subunit. This specificity illustrates why the inhibition of the 60S ribosome by Shiga toxin is a critical aspect of its role in bacterial pathogenesis.