The answer to why the Professor started liking the new India that he was reading about is option 'A' - "This country knew how to stand on its feet." Here's a detailed explanation:

The Context:
The Professor was reading about a new India, which implies that there had been significant changes and developments in the country. This new India was different from the one he knew, suggesting a transformation of some sort.

India's Ability to Stand on its Feet:
The key reason why the Professor started liking the new India was because it knew how to stand on its feet. This implies that the country had become self-reliant, independent, and capable of sustaining itself economically, socially, and politically.

Understanding Self-Reliance:
Self-reliance refers to a country's ability to meet its own needs without relying heavily on external support or aid. It means having strong domestic industries, a robust economy, and the capability to handle its own affairs.

Appreciation for Independence and Autonomy:
The Professor's liking for the new India indicates his appreciation for the country's independence and autonomy. It suggests that India had overcome its dependence on other nations and had gained the ability to make decisions and shape its own future.

India's Economic Progress:
The notion of India being able to stand on its feet also implies that the country had made significant economic progress. It had likely achieved a level of stability, growth, and prosperity that allowed it to sustain itself and its population.

Positive Implications:
The Professor's liking for the new India suggests that he saw positive implications for the country's development, progress, and potential. It indicates that he admired the country's ability to overcome challenges, become self-reliant, and emerge as a strong and prosperous nation.

Conclusion:
In summary, the Professor started liking the new India that he was reading about because it knew how to stand on its feet. This implies that the country had become self-reliant, independent, and capable of sustaining itself economically, socially, and politically. The Professor's liking indicates his appreciation for India's independence, autonomy, and economic progress, as well as his admiration for the positive implications of the country's development.