Rearrange the following words and phrases to make meaningful sentences.
(a) always/ the same/ Earth’*/ climate/ stayed / hasn’t
(b) an/ a **/ periodically/ of/ cold weather/ called /the/ goes through/especially / Earth/ ice age
(c) an/ during/ ice age,/ polar glaciers/ grow/ the / **.
(d) an ice age /at / of / glaciers/ the peak/ may cover/ a third/ as much as /the Earth / of