Question

Most basic amino acid among arginine histidine glycine glutamine

Answer 1

Histidine is the most basic ammino acid

Answer 2

There are three amino acids that have basic side chains at neutral pH. These are arginine (Arg), lysine (Lys), and histidine (His).

Their side chains contain nitrogen and resemble ammonia, which is a base. Their pKa's are high enough that they tend to bind protons, gaining a positive charge in the process.