Aminoglycoside antibiotics are not effective against amoebic dysentery caused by Entamoeba histolytica because:

The parasite has a cell wall that the antibiotics cannot penetrate.

The parasite has different ribosomes for protein synthesis than the bacterial ribosomes and is not susceptible to antibiotics.

The parasite has developed certain enzymes that deactivate/degrade the antibiotics leading to resistance to the aminoglycosides.

All of these.