I don't know how to solve this, can anyone do for me?

Which of these is most responsible for differences between the twentieth century to the twenty-first century?

During physical science class ben and jerry connected three identical lightbulbs in parallel to a battery where happens when ben removes one of the lightbulbs from it’s socket

Allison and her group have completed the data entry for their spreadsheet project. they are in the process of formatting the data to make it easier to read and understand. the title is located in cell a5. the group has decided to merge cells a3: a7 to attempt to center the title over the data. after the merge, allison points out that it is not centered and looks bad. where would the title appear if allison unmerged the cells in an attempt to fix the title problem?