When two companies involved in unrelated business merge, the merger is known as :

 Conglomerate Merger. 

What kind of MCQ people are asking at this professional site,

Answer: c Conglomerate  Merger

The Decision to merge/amalgamate results from one or more non deceicive factor which end up the Advantage/Disadvantage to any one--and both of them do not want take the uncertain risk. The decision to utilise their Assets and appropriate fixing of the product mix, and utilising their co-getters such a decision is taken- though it seems to be a rare option.