According to the NCERT text, IUDs increase phagocytosis of sperms within the uterus (Statement I). Copper releasing IUDs release Cu ions that suppress sperm motility and fertilising capacity (Statement II). Hormone releasing IUDs make the uterus unsuitable for implantation (Statement III) and the cervix hostile to the sperms (Statement IV). Statement V is incorrect because preventing semen from entering the female reproductive tract is the function of barrier methods (like condoms, diaphragms), whereas IUDs work inside the tract after insemination.