The correct answer is Option 2, "Singapore : Shcomp". All the options in this question refer to an association between a country and its primary stock market index, which is a tool that analysts use to describe the market and to compare the return on specific investments.

Option 1, "Japan : Nikkei," is correct because the Nikkei is indeed the main stock market index for Japan.

Option 3, "UK : FTSE," is right because FTSE (Financial Times Stock Exchange) refers to the 100 most capitalized companies listed on the London Stock Exchange, representing the UK`s primary stock market.

Option 4, "USA : Nasdaq," is also correct as Nasdaq stands for the National Association of Securities Dealers Automated Quotations, an American stock exchange. It`s actually one of two significant indexes in the U.S., the other being the Dow Jones Industrial Average.

However, Option 2 is incorrect. Shcomp is not the main stock market index for Singapore. In actuality, Shcomp, or the Shanghai Composite Index, represents the Chinese stock market. The index for Singapore is the Straits Times Index (STI).