Correct Option
Explanation:
Our blood is slightly basic in nature with pH range from 7.35-7.4
It is produced by decarboxylatron of histidine having following structure,
It is clearly visible from the above structure that histamine has two basic centres namely aliphatic amino group and basic nitrogen of imidazole ring, The aliphatic amino group has pKa around 9.4
ln blood with pH around 7 .4 the aliphatic amino group of histamine become protonated to give a single charged cation as shown below