4. Which оf the fоllоwing stаtements аbout pаttern recognition receptors (PRR) is true(1) Mammalian PRRs are located only on the membrane, but not in the cytosol, to recognize PAMPs to trigger immune responses. (2) Plant PRRs are located mostly on the membrane and recognize PAMPs to trigger immune responses. (3) TLRs and Nod-like receptors are pattern recognition receptors in mammalian cells.