The correct answer to this open question is the following.
Although you did not include options for this question, we can answer the following.
Remembering that water contains two hydrogen atoms and an oxygen atom is an example of what kind of Long-term memory.
When we are talking about long-term memory, we are referring to that the brain has the capacity to store and recall information learned years ago. Oftentimes, we have to make an effort to remember one thing and then, it comes to our minds. Other times we need a trigger or an outside impulse that makes us remember.
Other kinds of memory are Short-term memory and Sensory memory.