Concept:In very dilute strong acid solutions, the H+ contributed by water cannot be ignored.Explanation:10−8M HCl gives 10−8MH+ from the acid.Pure water supplies 10−7MH+, but this is suppressed due to the common ion effect.Hence, total [H+] is slightly more than 10−8M but less than 10−7M.As pH=−log[H+], this gives a pH slightly less than 7.Answer:pH<7, i.e., Option C.