The correct option is A Product of the numbers ÷ their L.C.M
The H.C.F of two numbers can be written as product of the numbers ÷ their L.C.M
For example, H.C.F of 60 and 72 can be written as:
60 × 72 ÷ L.C.M
L.C.M of 60 and 72 is 360.
∴ 60×72360
⇒ 4320360=12