i think the answer would be : C. somewhat acidic PH has the scale from 0 to 14 subsatance that has Ph of 0-7 is considered an acid and the susbtance that has the pH of 7-14 is considered a Base From the acid group, the substance that considered as 'extremely acid' are the one that has the pH between 0-2.5 . . .so the correct answer is CHope this helps. Let me know if you need additional help!