$(1)$ People today communicate in ways that earlier generations could have never dreamed of$.(2)$ They can now speak to each other almost anywhere using cell phones. $(3)\_\_\_\_\_,$ they communicate via email, text and instant messaging, Skype, Facebook, and Twitter.

$4.$ What word best completes the sentence?

a$.$ In addition

b$.$ To begin with

c$.$ Third

d$.$ Last