Language is a system of signs represrnting ideas to convey a message. Those symbols, which are words can be arbitrary, ambiguous, abstract representations of other phenomena. Words are not intrinsically connected to what they represent. Meanings of words can shift over time. The arbitrary character allows us to invent new words.
Language is ruled guided, simply put, verbal communication is guided by unspoken but broadly understood rules.
So I would say that option A, C and D are correct.
Meanwhile, I think that option B is incorrect since a mean of communication is understood as the tool and technology employed in order to convey a message, exchange information, ideas.
The correct answer is option D: A Haggle
If a buyer is haggling a seller for a better price and the seller holds its ground it means that the act of haggling demonstrates they both have competing interests since one of them is interested in buying for a lower price while the other is interested in selling for a higher price.
You have to be able to read word problems to solve word problems