AQA A-Level Physics question: Electric fields

I need help with part b) of the following question:

An insulated metal conductor is earthed before a negatively charged object is brought near it.

a) Explain why the free electrons move as far away from the charged object as they can.

b) The conductor is then briefly earthed. The charged object is then removed from the vicinity of the conductor. Explain why the conductor is left with an overall positive charge.

I understand that in part a) the delocalised electrons in the metal are negatively charged so they are repelled by the object but could someone please explain the theory of part b) to me? Many thanks.

The following video describes the induction process that you are looking for.
https://www.youtube.com/watch?v=mL6Zb2pO9CA

When the conductor is earthed, the electrons will flow to the Earth via the earthing connection, leaving the induced positive charges in the conductor.

Thanks I understand charging by induction now. Just one quick question when the conductor is left with an overall positive charge and the negatively charged object is taken away won't the conductor then be discharged by the earth though as the electrons are attracted back to the positive ions in the metal conductor due to the absence of the object?

...the conductor then be discharged by the earth though as the electrons are attracted back to the positive ions in the metal conductor...