The letters from A to Z are numbered from 1 to 26 respectively. If GHI = 1578 and DEF = 912, then what is ABC equal to?

First, we apply the 'Instant Letter-to-Number Mapping' concept [31] to the given examples. \n\nFor GHI: G=7, H=8, I=9. \nInstead of adding them, we look at the structure. The output 1578 is much larger than the sum (24). Following the 'Place Value System' logic seen in 2018 [15], we treat GHI as the number 789. \nNow we check the relationship between 789 and 1578. \n$789 \\times 2 = 1578$. The rule appears to be 'Concatenate digits and multiply by 2'. This matches the 'Doubling' or 'Linear Scaling' concept [19].\n\nWe verify this hypothesis with the second example, DEF. \nD=4, E=5, F=6 $\\rightarrow$ Number 456. \nApply rule: $456 \\times 2 = 912$. This matches the given value 912 perfectly. The rule is confirmed.\n\nNow, we apply the same rule to the target ABC. \nA=1, B=2, C=3 $\\rightarrow$ Number 123. \nCalculation: $123 \\times 2 = 246$.\n\nLooking at the options, 246 corresponds to Option D.