21...............................
Answer:
examples are:
com or .edu is a top-level domain name (TLD)
cornell.edu is a second-level domain name (SLD)
bigred.cornell.edu is a third-level or three-part domain name
project.bigred.cornell.edu is a fourth-level or four-part domain name
hope this helps you.
That would be an Ergonomic keyboard, due to the fact that it is laid out in such a way that doesn't harm your wrists
