演示的特点是（）强，能形象的表达抽象的问题。

A、直观性

B、实用性

C、实战性

D、效果性

Ab Co is a designer and manufacturer of highly specialist pressure transmitting systems. It required pressure sensors of a more than usual sensitivity for a particular contract. In search of the necessary components it approached Ba Co, a manufacturer of such equipment. In order to convince Ab Co of the suitability of their product Ba Co arranged for a technological evaluation of their sensors and were delighted when they more than matched the standard and announced the fact in their trade association journal. Ab Co was also delighted at the results of the tests and ordered the sensors from Ba Co.When Cy read the journal he was also sure that the sensors would be sensitive enough to function on a specialist project he was working on, so he also ordered a batch of the sensors from Ba Co.Unfortunately when Ab Co incorporated the sensors into its pressure transmitting systems they proved to be not as sensitive as it had been led to believe and caused the failure of the whole system. In fact the sensors were no more sensitive than normal sensors, available at a much lower price.Cy’s specialist project also failed because of the lack of sensitivity of the component sensors and he lost a valuable contract as a result.Required:Assuming that the UN Convention on Contracts for the International Sale of Goods applies, advise AB Co and Cy as to any rights and recourse they may have against Ba Co. (10 marks)