A basket on wheels = (a)  

A person or business that sells goods = (a)  

Increase the sales or popularity of something = (a)  

A space for walking between two rows of shelves or seats = (a)  

Moving stairs

(a)  

The greatest that is possible = (a)  

feeling very hungry = (a)  

A current medium of exchange in the form of coins and banknotes = (a)  

A person who buys goods or services from a shop or business = (a)  

The action or activity of buying goods from shops = (a)  

A large self-service shop selling foods and household goods = (a)