If the sender is not readily identified, we label it propaganda. Usually, propaganda is used to advertise political causes, and to persuade you into believing that particular promotion. They want you to join them, and to follow their leader, which is why they are promoting their own causes, whilst not identifying themselves.
The supply curve plots price on the vertical axis and quantity supplied on the horizontal axis.
The supply curve is upward sloping. This indicates the law of supply which says, the higher the price, the higher the quantity supplied and the lower the price, the lower the quantity supplied.