An urban poor, as per the year 2011-12, is defined as an individual or family living in an urban area with a monthly income of Rs1,000 per month per person. This definition is determined by the poverty line set by the Government of India to identify those living below the poverty line in urban areas. Let's delve deeper into the explanation:

Understanding the Poverty Line:
The poverty line is a threshold used to determine the minimum level of income or consumption required to meet basic needs and lead a decent life. It is calculated based on the cost of a basket of goods and services necessary for subsistence, including food, clothing, shelter, education, and healthcare.

Determining the Urban Poverty Line:
The poverty line for urban areas is higher than that for rural areas due to the higher cost of living in cities. The poverty line is revised periodically to account for inflation and changes in living standards. In 2011-12, the poverty line for urban areas in India was set at Rs1,000 per month per person.

Explanation of Option C:
The correct answer, option C, states that an urban poor as per the year 2011-12 has an income of Rs1,000 per month per person. This means that individuals or families earning less than Rs1,000 per month per person in urban areas during that period would fall below the poverty line and be classified as urban poor.

Other Options:
The other options mentioned in the question, such as Rs450, Rs500, and Rs454 per month per person, are lower than the poverty line set for urban areas in 2011-12. Therefore, individuals or families with these income levels would also be considered urban poor.

Conclusion:
To summarize, an urban poor as per the year 2011-12 is an individual or family living in an urban area with a monthly income of Rs1,000 per month per person. This poverty line is set by the Government of India to identify those living below the poverty line in urban areas. The options mentioned in the question, such as Rs450, Rs500, and Rs454 per month per person, are all lower than the poverty line, making option C the correct answer.