Question

Which of these is a pure substance?

Answer 1

B. Sugar.

A penny is an alloy of zinc and copper, usually. This is a substance that has been mixed with something else and is no longer pure.

Ocean water isn't just water either, it's water, salt, waste, etc.

Iced tea is a mixture as well.

Sugar is a pure substance because it hasn't been mixed with anything else and it would be impossible to make it even purer without breaking it down into elements.

Answer 2

B. Sugar is a pure substance.
It is sugar because sugar is made up of one atom or molecule. 
A) penny is not correct because a penny is made up of copper, zinc, and tin.
C) ocean water is not correct because its made out of water (h2o) and salt.
D) iced tea is not correct because it takes many atoms to combine in order to make tea, then you have to add water and ice to make it an iced tea.

Hope this helps! :)