C. The sensitivity of the retina decreases
The nurse should assure the patient that black tongue is an expected side effect of taking that particular drug. The active ingredient in the drug contain bismuth. The tongue and the alimentary canal of humans contain trace amount of sulphur, when bismuth comes in contact with this sulphur, bismuth-sulphide will be formed. Bismuth-sulphide is an harmless by product, thus, the tongue discoloration observed in the patient is harmless.<span />
Answer:
Having a zygotic constitution of a specified kind:heterozygous.
