The correct option is D All of the above
Mycoplasma genitalium is a pathogenic bacterium that causes STD. It lives on the ciliated epithelial cells of the urinary and genital tracts of humans. Mycoplasma hominis is associated with the urogenital mucous membrane and causes STD. It may lead to pelvic inflammatory disease, which causes ectopic pregnancy. Mycoplasma pneumoniae is a bacterium that causes infections of the respiratory system. All three strains are harmful to humans. Thus, the correct answer is option D.