In each of the following questions, three sentences are given, each employing a specified idiom or phrase highlighted in bold. Identify the sentence(s) in which the idiom/phrase has been used correctly in terms of meaning and context. Choose the option that best reflects the correct sentence(s). If none of the sentences use the idiom correctly, choose Option E (None is correct).
I. The lead scientist hit the nail on the head when she identified ground-level ozone as the primary smog precursor.  
II. High-speed railway engineers hit the nail on the head by failing to inspect underground water dispensing networks properly.  
III. Do workplace wellness programs hit the nail on the head when they address employee burnout through mandatory overtime?