Clicking the deletes all letters in a box.

it would be a. excessive network collisions or d. slow connectivity between devices those would be my answer.

solution:

the right option is a

to adding   a new row to a table we   have to do process last table cell and pressing tab.

this is the process to add new row in the cell:

* to add a row below the cell, click insert below in the rows and columns group.

thus this is the required right answer.