In the following passage some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each blank.
People make plastic products by mixing the plastic with additives. The additives (1) ______ it difficult to recycle the plastic. To recycle plastic things, (2) ______ grind them up first, but this new (3) ______ is not easy to use again. A laboratory in California made a new type(4) ______ plastic to deal with this problem. (5) ______ scientists put the new plastic in a highacid solution, the plastic and the additives break apart. People can then easily reuse the plastic.
Select the most appropriate option for blank No. 4.