From the options above, the closest is the US, but even the US does not have a pure market economy, as some aspects of the economy are regulated by the government: for example education.
Since none of the options have a pure market economy, the correct answer is d: none of the above.
China has a command economy, which means that the government controls even more than in the US (almost everything). UK is more similar to US, but still a lot of its economy is controlled by the government.