Histamine is mainly found within storage granules of mast cells but also found in other tissues like:: (A) Gastric mucosa., (B) Oral mucosa., (C) Inner epithelium., (D) All of the above.
Answer is A. Histamine is mainly found within storage granules of mast cell but also found in other tissue 

Mast cell histamine – mast cell and basophile. 
Non mast cell histamine – Gastric mucosa.