How is the bond formed in the structure of a dinucleotide?

• A
  Between the $-NH_2$ group of one nucleotide and the $-COOH$ group of another nucleotide.
• B
  Between the $3'-OH$ group of one nucleotide and the $5'$-phosphate group of another nucleotide.
• C
  Between the $1'-OH$ group of one nucleotide and the $4'-OH$ group of another nucleotide.
• D
  Between the $-CONH_2$ group of one nucleotide and the $-OH$ group of another nucleotide.