How Is a Dipeptide Formed

How is a dipeptide formed?

A) The -NH₃⁺ group of one amino acid forms an amide bond with the -NH₃⁺ group of another amino acid and the elements of H₂ are removed.
B) The -NH₃⁺ group of one amino acid forms an amide bond with the carboxylate (-COO^-) of another amino acid,and the elements of H₂O are removed.
C) The carboxylate (-COO^-) group of one amino acid forms an amide bond with the carboxylate (-COO^-) of another amino acid,and the elements of O₂ are removed.
D) The carboxylate (-COO^-) group of one amino acid forms an amide bond the -NH₃⁺ group of another amino acid,and the elements of H₂ are removed.