The correct answer is a. staff-selected activities. Children should be allowed to choose free time activities as well as participate in activities selected by the staff, because their activities are thus directed to the best possible way, leading to relaxation, games and still creative.
Watching TV can not replace free activity in a positive sense, especially if we know how many children today sit in front of TV, computers.
Harder activities should also be avoided in the free time, because it primarily serves for a creative break from the thinking activities.
Also, imposed choices should also be avoided, and leave children free choice.