Read the following dialog and choose the correct answer.

Source: hbforward.en.made-in-china.com

Wendi       : What tool is that, Sir?
Mr. Naufal  : That is a spade. I use it to ... or clean the ditch.
Wendi       : I see.

Mr. Naufal said, "That is a spade. I use it to ...."

The underlined word refers to ....