Which of the following companies allows its shares to be purchased by the public?

A public listed company is the correct choice because it is specifically structured to allow its shares to be purchased by the general public on stock exchanges. This means that anyone can buy shares, thereby participating in the ownership of the company. Public listed companies must comply with regulatory requirements, including disclosures and reporting, making their financial information available to potential investors.

In contrast, a private limited company restricts the sale of its shares, typically only allowing them to be sold to a select group of investors. A sole trader operates the business as an individual and does not issue shares at all, as there aren't multiple owners. Similarly, a partnership consists of two or more individuals who share ownership and management responsibilities but do not issue shares to the public. These structures focus on smaller, private ownership rather than public trading of shares, which is the hallmark of a public listed company.