新东方逻辑题请教

Partly because of bad weather,but also partly because some major pepper growers have switched to high-priced cocoa,world production of pepper has been running well below worldwide sales for three years.Pepper is consequently in relatively short supply.The price of pepper has soared in response:it now equals that of cocoa.

Some observers have concluded that the rise in the price of pepper means that the switch by some growers from pepper to cocoa left those growers no better off than if none of them had switched;this conclusion,however,is unwarranted because it can be inferred to be likely that

a,

b,

c,supplies of pepper would not be as low as they are if those growers had not switched crops.

请问 left those growers no better off 是什么意思，为什么答案是c。多谢了