People litter for a variety of reasons, and all of the options provided - selfishness, laziness, and ignorance - contribute to this behavior. Some individuals may litter out of selfishness, prioritizing their own convenience over the cleanliness of their surroundings. Laziness can also play a role, as some people may not want to take the time or effort to properly dispose of their waste. Additionally, ignorance can lead to littering, as some individuals may not be aware of the negative impacts it has on the environment and communities.