Final answer:
The most valuable nursing assessment when formula seems to stick in a baby's mouth is to Inspect the baby's mouth and throat, as this can reveal conditions like oral thrush. Further steps depend on initial findings.
Step-by-step explanation:
When a mother reports that formula seems to stick to her baby's mouth and tongue, the most valuable nursing assessment would be option A) Inspect the baby's mouth and throat. This initial step is crucial as it could reveal the possible presence of oral thrush, a common fungal infection in infants characterized by white patches on the tongue and inside the mouth. An inspection would involve, similar to a typical medical exam, the use of a tongue depressor to check the back of the mouth and the oral cavity's opening into the pharynx. It is important to perform this step professionally and gently, considering the comfort of the infant as well as the concern of the parents.
If upon inspection the white patches cannot be easily wiped away and the underlying tissue might be red and possibly bleeding, this would suggest oral thrush rather than milk residue. Further steps might include obtaining cultures or prescribing antifungal treatment, but that would be determined by the health care provider after assessment.