In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[EX Q]: Comets are a bit like giant dirty ice-balls with diameters between _ and fifty kilometres.
[EX A]: five

[EX Q]: Pelycosaurs are a paraphyletic group of _ primitive families of synapsids.
[EX A]: six

[EX Q]: Most transsexuals report being aware of their condition from the age of _ to seven.
[EX A]:
four