B is wrong because of two reasons-
1. The first part of the sentence no where having a proper comparison with the latter part i.e
Unlike the shuttle and earlier spacecraft, with sufficient enough power in fuel cells and batteries for their short flights ---- > this part just says that shuttle and spacecraft are having sufficient enough power xxxxxx
latter part says that orbitting space station will have to generate i.e do some action
2. Earlier spacecraft means that something which used to happen in the past but option B by the usage of with is predicting that it's presently this and the same is wrong because it changes the intended meaning of the sentence
