Certificate of commencement of business is not required by:

A public company
A private company
Both public and private company
Private company subsidiary to a public company

The correct answer is: D. Private company subsidiary to a public company.

A certificate of commencement of business is a document that is required by the Companies Act 2006 to be filed with the Registrar of Companies when a company is formed. The certificate is evidence that the company has been properly formed and is authorized to carry on business.

A public company is a company that has a share capital that is divided into shares that are offered to the public for subscription. A private company is a company that is not a public company.

A private company subsidiary to a public company is a private company that is wholly owned by a public company.

The Companies Act 2006 does not require a private company subsidiary to a public company to file a certificate of commencement of business. This is because the public company is already required to file a certificate of commencement of business on behalf of its subsidiary.

The other options are incorrect because they are all types of companies that are required to file a certificate of commencement of business.