You are asked to “assesses the extent to which the suggested KPIs would be suitable for use in planning rather than controlling”. So you have to assess the suitability of the KPIs for planning; you do no have to conclude whether planning is good or not, so benchmark data is not needed here.
Mu own view is that most of the KPIs can be used for both planning and control. For example, market share can be backwards looking and forwards looking where a target is set. Similarly, profit and contribution per unit where you could plan to sell more of teh most profitable product.
Really, I think all it wants is a sensible discussion of the KPIs and different popple can argue for different conclusions.