Option (1) is the correct answer because, ligases are the enzymes that catalyse the linking together of 2 compounds, e.g., enzymes which catalyse joining of C−O,C−S,C−N,P−O etc. bonds. ⇒ Options (2), (3) and (4) are wrong as ligase catalyse the joining of P−O,C−O&C−N bonds.