Is 'the' needed in front of the word 'key' in this sentence?
Here is the sentence:
MPs said the introduction of a plastic bottle deposit return scheme (DRS) was key to reducing plastic waste in the UK, as part of a series of measures to reduce littering and increase recycling rates.
I was taught the phrase 'the key to sth' at school, but then I read this today. Is it acceptable to say key to reducing plastic waste without the? How about adding the, does it make any sense?