The correct answer is: " a company owns stock in several different corporations".
A holding is a type of corporation does not provide goods or services, but simply owns stock from other companies in order to constitute a corporate group. It is a manner of reducing risk for investors/owners.
The other definitions provided correspond to the following phenomena:
- absortion and monopoly: a railroad company buys its competitors'
- collusive oligopoly: companies leaders from different transport companies agree to charge the same prices
- vertical integration: a paper factory owns a lumber yard and paper mill