Concept:Home trade documents are used for transactions within one country, while foreign trade documents are used for international trade.
Explanation:A bill of lading is issued for goods carried by sea, so it is mainly linked to foreign trade.
An airway bill is issued for goods carried by air, so it is also mainly linked to foreign trade.
A certificate of origin shows where goods were produced, which is usually needed in foreign trade.
A proforma invoice is a preliminary document sent to the buyer before actual supply of goods, and it is commonly used in home trade within a country.
Therefore, the document used only in home trade is the proforma invoice.
Answer:D. proforma invoice