Man does not seek self-improvement because he

• (a) is not intellectually capable — Incorrect. The statement is too absolute; self-improvement is not denied mainly due to lack of intellect.
• (b) has no time to do so — Correct as per the accepted key. In such value/philosophy-based questions, the intended idea is that man remains occupied in worldly engagements and therefore does not devote time to self-improvement.
• (c) is distracted by materialism — Incorrect. This may be a contributing factor, but it is not the specific reason intended here.
• (d) loves amusement and is mentally idle — Incorrect in the exam context. Though philosophically arguable, it is not the answer supported by the official UPSC key.

Note: This is a philosophy/value-based question, so interpretation can vary. My earlier choice of (d) was based on a broader philosophical reading, but for exam purposes (b) should be accepted.