In the question given below, a sentence is given, divided into parts. One of the parts may contain an error. Identify the part that contains the error, and mark it as the answer. Ignore errors of punctuation. In case the sentence is correct as it is, mark option (e), that is, 'No error'. Note - The words in bold are grammatically and contextually correct. A decade ago, NASA chose Boeing and an upstart rival , SpaceX, to ferry astronauts to and from the space station and SpaceX since carried out seven of those missions while Boeing has yet to complete one .