$A$ piece of foreign $DNA$ can replicate if it is linked to which of the following?

Which enzyme is used to synthesize a $cDNA$ probe from a messenger $RNA$ molecule?

Which of the following is not a cloning vector?

In the restriction endonuclease $Eco RI$,what does the part '$co$' stand for?

Which of the following is not a selectable marker?

About gene gun method:
$I.$ This method is also known as biolistic technique.
$II.$ In this method,cells are bombarded with high-velocity micro-particles of gold or tungsten coated with $DNA$ in plants.
$III.$ Important crop plants like maize,rice,and wheat have now been transformed by this method.
Which of the statements given above are correct?