Briefly explain what the maximin rule entails (is used to determine), and what decision-maker will make use of the maximin rule

If the maximin rule is applied, the highest of the worst profit for each of the options will be chosen.
OR
The “play it safe” basis for decision making is referred to as the maxmin basis. This is short for “maximize the minimum achievable profit”.
Maximin decisions are taken by risk-averse decision-makers.