Which of the following did not allow researchers to further explore below the ocean's surface?

he could use bold or bigger text just a suggestion.

answer is:

a). backstage view

explanation:

backstage view is the area where files and data about them is managed— creating, saving, printing, sending to others, inspecting for hidden metadata or personal information, and setting options. so in this way we can add many things to our document swiftly.

i hope you get the idea.