Which of the following words means "lack of care"?

The word "careless" means a lack of care or attention to detail. When someone is described as careless, it implies that they are not paying sufficient attention to their actions or the consequences of those actions, which often leads to mistakes or accidents. This aligns perfectly with the idea of a "lack of care."

In contrast, the other options convey different meanings. "Hopeful" relates to having optimism or expecting a positive outcome. "Careful" indicates attentiveness and caution, which is the opposite of what is meant by a lack of care. "Dislike" expresses a feeling of aversion or not liking something, which does not connect to the concept of care or attention. Therefore, "careless" is the word that accurately reflects the meaning of "lack of care."