Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer

PLASTIC AND THE ENVIRONMENT

Plastic is a material we use every day. The first plastics were made more than 100 years ago from parts of plants. Plastics are now made from oil, coal and natural gas. We are using up these things so fast that the Earth’s supplies may run out. Because of this, scientists are investigating new ideas for making plastics from plants such as sweet potato, bamboo and flax.

Things made from plastic can be useful for people but bad for the planet. Some plastics can last for a long time without wearing out, and can be difficult to get rid of when they are not needed. They can remain in rubbish dumps called landfill sites for hundreds of years. Landfills can be smelly, ugly, and harmful to our planet.

Recycling is a good way to get rid of unwanted plastics. Recycled waste materials can be used again to make new products. This can be difficult as different types of plastic need to be recycled in different ways. Some kinds of plastics can be melted down and used to make new things such as bags and bottles. Others can be made into fibres (strands of material) for clothing.

Another way to protect the environment is to use canvas bags for shopping rather than plastic ones. A lot of plastic objects can also be reused. Plastic bottles can be refilled many times, rather than throwing them away once they are empty. Unwanted plastic goods such as CDs and toys can be sold or given away to charity shops.

(Adapted from: https://www.esolcourses.com)

The phrase “empty” in the last paragraph is closest in meaning to ______.