Initial public offering is undertaken through the

Explanation

The primary securities market is where new securities, such as stocks and bonds, are issued and sold for the first time. This is where companies raise capital by selling their shares to investors. IPOs are one of the primary methods used by companies to raise funds for expansion, research and development, or other business activities.

On the other hand, the secondary securities market, mentioned in Option B, is where already issued securities are traded among investors. This includes stock exchanges where investors can buy and sell shares of publicly traded companies.

Options C and D, first-tier and second-tier securities markets, are not commonly used terms in the context of IPOs. It's important to focus on the primary securities market as the correct answer.

To summarize, an initial public offering (IPO) is undertaken through the primary securities market, where new securities are issued and sold to the public for the first time. This allows companies to raise capital and investors to become shareholders in the company.