The correct answer to this open question is the following.
Although she remembers riding the bus every day to school, Hillary especially remembers the day that her bus driver was dressed up like a clown. this type of memory would be described as autobiographical memory.
When our brain collects different episodes of our life, we can say we are using our autobiographical memory. It could be objects, experiences, specific moments that impressed us or events that impacted and left a strong mark in our minds. That is why Hillary especially remembers the day that her bus driver was dressed up like a clown. It caused a special impression that was ingrained in her memory.