The Nurse Notices a Stain on a Newly Dried Plaster

The nurse notices a stain on a newly dried plaster cast over a client's fracture site. The most appropriate method to assess this finding is to

A) assess for a "hot spot" over the stain.
B) bivalve the cast and inspect the site.
C) draw around the circumference with a pen and record.
D) dry the stained area of the cast with a hair dryer.