It's a supplier quotation.
Both the RFQ and the PQQ (sometimes known as 'SQ') are issued by the buying side, not the sell-ing side.
A commercial invoice doesn't tell you what the price 'would be' - it tells you what is owed after the event (usually - an exception being with prepayment in mind; or a 'proforma invoice' which is issued in some circumstances, especially internationally).

A market with only one buyer is called a 'monopsony'.
There may be other questions in this test about the other terms shown, so I shall hold back on expla-nation(s) here.

This is a broad group of people deriving income from employment, including some skilled people through to unskilled.
A, B and C1 would be those people often referred to as upper middle class or upper class; whereas E would describe a broad group of the poor, the unemployed, etc.
These are rough generalisations regarding people's likelihood of income, taste, lifestyle, etc. To take an extreme example, there is probably not much point in trying to market Dom Perignon (an expen-sive brand of champagne) to the E group. But the E group might welcome promotion of a low-cost brand of tobacco or cigarettes.

The x-axis shows time. For some products, it may represent a year; for others, a century.
The other answers given could all be shown on the y-axis of the PLC, depending on circumstances.