I'm no expert, but isn't this a bad question? If the HCF of two numbers is 6 then the other number must be a multiple of 6. The answer has to be 72, because the lowest common multiple of 6 and 12 is 72. LCM means the lowest number you can get by multiplying two numbers together.
Yes, because I was replying Jackdaw33's post immediately before mine
where it was suggested "LCM means the lowest number you can get by multiplying two numbers together". So i gave an example of 4 and 8 which when multiplied give 32, but the LCM is only 8