The companies which are formed under special act, are known as:

statutory companies
chartered companies
registered companies
government companies

The correct answer is: A. statutory companies.

A statutory company is a company that is formed under a special act of Parliament. This means that the company’s powers and privileges are set out in the act, and it is not subject to the same rules and regulations as other companies. Statutory companies are often formed to carry out a specific task or function, such as providing a public service or regulating an industry.

A chartered company is a company that is granted a charter by the Crown. This means that the company has a special status and is subject to different rules and regulations than other companies. Chartered companies are often formed to carry out a commercial or industrial activity.

A registered company is a company that is registered with the Companies House. This means that the company has a legal identity and is subject to the Companies Act 2006. Registered companies are the most common type of company in the UK.

A government company is a company that is owned or controlled by the government. Government companies are often formed to carry out a public service or regulate an industry.

In conclusion, the correct answer is: A. statutory companies.