Although according to the EU-funded Psychonaut Research Project it has only been available since 2008, mephedrone is now the fourth most popular recreational drug in the United Kingdom. Also known as meow meow and drone, mephedrone is a synthetic stimulant that is derived from cathinone compounds found in the khat plant of Eastern Africa. Chemically similar to amphetamines, mephedrone has the effect of euphoria and increased stimulation. Because it is sold as plant fertilizer and thus not subject to medical regulations, mephedrone is currently legal in the United Kingdom, although it has been banned in many other countries, including Sweden, Germany and Israel. Manufactured in China and sold cheaply, the drugs legality and availability have led to its meteoric rise. While it is not illegal, it does not follow that mephedrone is safe to use  an international lack of scientific research means that its effects on health are not fully known. Following reports of addiction and the drugs suspected involvement in several deaths; there are calls in the UK to have mephedrone classified as an illegal substance immediately. This legal decision, however, cannot be taken until a government advisory council has fully investigated any scientific evidence.

Question: The UK government has been criticised for failing to act quickly to criminalise mephedrone.
Options:
A. true, B. false, C. uncertain
Answer: "C"