Which statement is an example of a metaphor? the sand was very comforting. the sand was a warm blanket. the sand was as soft as powder. the sand was delicate and soft.

The sand was a warm blanket. is a metaphor.

A simile uses the words 'like' and 'as' to compare. 
so the sand was as soft as powder would be a simile

A metaphor is like a simile but doesnt use the words ' like' and 'as'. a metaphor is direct. an example of this would be...

she runs like a cheetah. ( she doesn't actually run like a cheetah though)  

hope i helped

Do you have a link to the reading?