(a) That not the best answer. It is important for persons who deal with a business to know whether or not its liability is limited. Accordingly, it is required that a company with limited liability must include the abbreviation 'Ltd' in its name. For example, a proprietary company would be called ABC Pty Ltd; a public company would be called ABC Ltd.
Not every company has limited liability. Sometimes companies are created where the rules of the relevant profession prevent the limitation of the members' liability. An example of this is where practicing lawyers set up a company for their business.