Which language is the most common for worldwide trade and business?
a) mandarin chinese
b) spanish
c) english
d) hindi

C) English

Explanation:

English is the most common language used in worldwide trade and business, and the US dollar is the most commonly used currency in worldwide trade and business.

Even though Mandarin Chinese is the most spoken language in the world, its influence is not very large outside of southern Asia. English is so commonly used as a universal language between different countries, that the European Union still uses it as its official language even though the UK is leaving them and only Ireland speaks English.

About 60% of the total US dollars are held outside the US and are generally used as a hard currency for trade operations.  

i would say iii (3) because in order to compare a price you have to use as a reference other near stores because it's its

hope i explained myself