Hunter-gatherers primarily learned to use the natural environment through direct observation and interaction with their surroundings. Of the options listed, the most relevant to their way of life would be:
They used wood and stone to make tools.
Hunter-gatherers developed various tools from available natural materials, like wood and stone, to aid in hunting, gathering, and other necessary tasks for survival. Their intimate knowledge of the environment helped them utilize resources effectively, such as identifying edible plants, understanding animal behavior for hunting, and making tools that suited their needs.
The other options mentioned (using wind for windmills, using rivers for irrigation, and using fire for farming) are more associated with agricultural practices that emerged later in human history, during the Neolithic Revolution, when people transitioned from a hunter-gatherer lifestyle to settled farming communities.