The human immune system detects the presence of pathogens using pattern recognition receptor molecules that bind to common components of pathogens, such as peptidoglycan polymers in cell walls and the flagellin protein of bacterial flagella, known as pathogen-associated molecular patterns, or PAMPs. These receptors are effective becauseGroup of answer choicesthey detect only human immune molecules. they result in rapid evolution of the host immune system. they recognize evolutionarily conserved molecules that are structurally essential to the various bacteria that use them. PAMPs evolve more quickly than other pathogen molecules.