Final answer:
Clients with head lice or scabies should be isolated in contact precautions to prevent the spread of the infection through direct contact or contaminated items.
Step-by-step explanation:
A client who is newly diagnosed with head lice or scabies should be isolated in contact precautions. These conditions are transmitted through direct skin-to-skin contact or by contact with an infested person's clothing, bedding, or other personal items. Therefore, the correct answer is A. is isolated in contact precautions. Health-care workers need to take appropriate precautions, such as hand hygiene and careful disinfection of all items coming into contact with the infected individual to prevent the spread of these infections.