From the options given below, choose the word which is most similar in meaning…

Concept: In a synonym-based vocabulary item, the correct option must share the SAME core sense as the target word, not merely a loosely related idea. 'Careless' describes a lack of due care or attention that leads to mistakes or unintended harm.

Application: Among the four options, 'Negligent' carries this exact sense — it means failing to give proper care or attention to a duty or task. Standard dictionaries (e.g., Merriam-Webster, Collins) list 'negligent' as a direct synonym of 'careless', so it is the word most similar in meaning.

Cross-check — the other options:

• 'Indifferent' centers on a lack of interest or emotional concern (apathy), not on inattentiveness to a task — a different sense from 'careless'.

• 'Arrogant' centers on an exaggerated sense of one's own importance, unrelated to attentiveness.

• 'Vigilant' centers on careful, watchful attention — the opposite sense of 'careless'.

Since only 'Negligent' shares the exact sense of lacking due care, it is the word most similar in meaning to 'careless'.