Which of the following statements about ddNTPs is true?
They have an oxygen at the 2 ' carbon of the sugar.
They have a free [tex]3^{\prime}[/tex]-hydroxyl group on the sugar.
DNA polymerase can add a new dNTP to a [tex]3^{\prime}[/tex] ddNTP.
They have a hydrogen at the [tex]3^{\prime}[/tex] carbon of the sugar.