Which of the following is a disadvantage to the coal-to-liquid production of synthetic fuels

A disadvantage of coal to liquid production of synthetic fuels is THAT IT REQUIRES MORE COAL MINING.
The coal to liquid production of synthetic fuels involves the conversion of solid coal to liquid fuel.This can be done either directly or indirectly through chemical processes. The process has many advantages, including: improvement in national and economic security, less dependence on foreign oil, provision of some environmental benefits, such as cleaner oil. But one disadvantage of this process is that it requires extensive coal mining.