which market structure is sainsburys plc under?

Answer 1

Start by checking the definition of Market Structures (http://www.bized.co.uk/educators/16-19/economics/firms/lesson/marketstructure.htm)
& http://en.wikipedia.org/wiki/Market_structure)

Then check current UK supermarkets Market Share (eg here = http://www.fooddeserts.org/images/supshare.htm a bit out of date but gives you some idea)

Finally compare Market Share against Market Definitions ...


NB. You need to learn how to do your own research (you could also try attending class, reading the set books etc).