15) C

By reading the passage, we can see that the underlying message that is being given to us is that people do not use words such as ‘umpteen’ and ‘zillion’ randomly to describe any number. People use ‘umpteen’ only to describe size generally below 100 and ‘gazillion’ to describe size above billion or ‘zillion’.

This means that there are certain rules and conditions that people follow as to when these words should be used.

e.g. people will not use ‘gazillion’ to describe a size below 100.