Diagnosis (Treatment): A 25-year-old woman presents with a five-year history of watery, non-bloody diarrhea and recurrent bacterial pneumonias. Laboratory studies show iron-deficiency anemia with low 25-OH Vitamin D. celiac serologies are negative, and small bowel biopsies reveal near-total villous atrophy, increased intraepithelial lymphocytes and crypt hyperplasia with absent plasma cells.

a) Celiac disease
b) Inflammatory bowel disease (IBD)
c) Short bowel syndrome
d) Giardiasis