Basic amino acid (s) is/are: (A) Arginine, (B) Lysine, (C) Histidine, (D) All of these
Answer is D. Basic amino acids → Histidine, arginine, lysine (Memonics HAL).
Acidic amino acids → Aspartic acid (aspartate), glutamic acid (glutamate).
All other 15 standard amino acids are neutral.