Question

Which word does the pronoun "it" refer to in the sentence?Kettles
     A kettle is a metal container used to boil water. Some kettles go on the stovetop, while some can be plugged into an electrical outlet. A kettle is filled with liquid, usually water, and placed on a heat source, so that the liquid inside of it will begin to boil. Once the water boils, steam is forced through two small holes in the spout of the kettle, causing a high-pitched whistling sound.

a: water
b:liquid
c:kettle
d:source
pueden eligir varias 

Answer 1

c: kettle.
porque esta hablando de que al poner el kettle en el heat source el liquido que contiene detro del kettle empieza a hervir.