Javier's little sister tends to bother him while he is doing homework. Javier wants to figure out which toy will keep his sister occupied the longest, so he will not be bothered. Javier decides to conduct an experiment where each day at 6 PM for a week, he gives his sister a different toy and on one of the days, he gives her no toys to play with. Javier measures the amount of time his sister spends playing with each toy before she comes to bother him. Which of the following is the independent variable in this example? Amount of time spent playing with the toy

Day of the week

Homework assignment being completed

Time of day

or Toy being offered