hey, i am unsure on how to do this question (mainly on the reasons for the prevalence of this type of market structure and the strengths and weaknesses of the AGR sector)

Coles and Woolworths dominate the Australian grocery retail (AGR hereafter) sector. Which type of market structure does this sector resemble? Explain the likely reasons for the prevalence of this type of market structure in the AGR sector.

Is the dominance of Coles and Woolworths in the AGR sector strength or a weakness for the Australian economy? Explain using relevant examples.