Replacing of plastic cups by the paper cups for selling tea on train is preferred
because
a) paper cups are more aesthetic
b) paper cups are more hygenic
c) paper cups are cheaper
d) paper cups are eco-friendly and biodegradable

Thanks !

Dear student,
Please find below the answer:

The correct option is (4).
Paper cups are eco-friendly and biodegradable while plastic cups are non-biodegradable. This is why replacing of plastic cups by paper cups is preferred for selling tea on trains. 

Hope this clears your doubt.
Regards.