For two of three generations past, ever-increasing numbers of individuals have been living as workers merely, not as human beings. An excessive amount of labour is rule today in every circle of society, with the result that man’s spiritual element cannot thrive. He finds it very difficult to spend his little leisure in serious activities. He does not want to think; or he cannot even if he wants to. He seeks not self-improvement, but entertainment which would enable him to be mentally idle and to forget his usual activities. Therefore, the so-called culture of our age is dependent more on cinema than on theatre, more on newspapers, magazines and crime stories than on serious literature.

Man does not seek self-improvement because he

The correct option is: has no time to do so.

Step-by-Step Explanation:
1. Analyze the passage's premise: The text starts by pointing out that modern individuals live "as workers merely, not as human beings" because "an excessive amount of labour is rule today in every circle of society."
2. Examine the consequence of overwork: As a direct consequence of this constant and excessive labor, the passage states that man "finds it very difficult to spend his little leisure in serious activities." Here, "little leisure" indicates a severe lack of free time.
3. Connect to self-improvement: Because his free time is so limited and his energy is consumed by work, man does not seek self-improvement (which requires active, focused mental effort during leisure). Instead, he turns to easy entertainment to mentally rest and forget his daily work.
4. Conclusion: Thus, the root cause of why man does not seek self-improvement is that he has "little leisure," meaning he has no time to do so due to the excessive demands of labor.