To save time, a document that will be used repeatedly should be saved as ________

What is the default file extension for a regular Excel 2016 document?

A) .xls B) .xltx C) .xlt D) .xlsx

________ is a serial computer bus typically used for attaching lower-speed peripheral ICs to processors and microcontrollers in short-distance, intra-board communication.

Fill in the blank(s) with the appropriate word(s).