What is the only possible phenotype of an offspring produced from two group

What is the only possible phenotype of an offspring produced from two group O parents?
a.   A   
b.   B   
c.   AB
d.   O

A patient who was recently diagnosed with an obstructed bowel became septic from Proteus vulgaris. Prior to surgery, a routine type and screen was performed. Though this person typed as an A two years ago, his forward type is consistent with an AB individual, albeit weaker in strength with anti-B. What is the reason for this discrepancy?
a.   Acquired "B"   c.   Incorrect patient history
b.   Technical error   d.   Contaminated anti-A


What immunodominant sugar is responsible for B specificity?
a.   D-galactose   c.   N-acetyl-D-galactosamine
b.   L-fucose   d.   D-glucose