The correct answer is:

III. FTSE - 100 : London

Explanation:

I. Dow Jones is correctly matched with New York. The Dow Jones Industrial Average (DJIA) is a stock market index that represents 30 large publicly traded companies based in the United States. It is widely regarded as a barometer of the overall stock market performance in the United States, and it is indeed associated with New York.

II. Hang Seng is incorrectly matched with Seoul. The Hang Seng Index (HSI) is a stock market index that represents the 50 largest companies listed on the Hong Kong Stock Exchange. It is associated with Hong Kong, not Seoul. Therefore, this pair is incorrect.

III. FTSE-100 is correctly matched with London. The FTSE-100 Index, also known as the Financial Times Stock Exchange 100 Index, is a stock market index that represents the 100 largest companies listed on the London Stock Exchange. It is widely regarded as a benchmark index for the UK stock market and is associated with London.

Based on the above analysis, the correct pair is:

I. Dow Jones: New York

III. FTSE - 100: London

Therefore, the correct answer is I and III.