please answer a , b, and c from fiven answer I don't need any explanation.

The list 10km _ times contains times, in minutes, taken by runners to run a 10km race. The when [space] key_pressed script below should calculate and display the average (mean) of the times in the list, or tell the user that the list is empty. So for example if 10km - times has the contents shown in the watcher below then the message 'Average time in minutes is 52.6 ' should be displayed. The program is incomplete at the points labelled a, b and c. Select the code (in textual form) that should be inserted at each of these points