Why was catherine the great considered an efficient ruler

She was considered an efficient ruler for different reasons. Some of them are that she had built good relationships with Australia and Prussia and she made territorial advances at the expense of the Tartars and the Turkish. She also introduced reforms to increase Russia's wealth and applied modern scientific methods to agricultural. 
That's just a few things that made her great.
I hope those few help you! :)

Ibelieve b) recall election

Pilgrims is the answer