What does this traffic sign indicate?

The sign indicates the presence of a natural gas fuel station (CNG - compressed natural gas). In Germany, such signs are used to inform drivers of alternative fuel options available at filling stations, promoting the use of cleaner energy sources. The correct answer includes the option for a natural gas fuel station because it's specifically denoted by the "CNG" label. Other options, like hydrogen and auto gas, refer to different types of fuel stations that would have separate signage. Understanding these distinctions is essential for drivers seeking alternative fuels, especially in the context of increasing environmental regulations and the push for greener vehicles.