The cia planning was extraordinary. questions were asked. problems were anticipated, solutions suggested. with information provided by an informant in the soviet state-run telephone operation, the u. s. knew that the spot they needed to reach with the tunnel was under schonefelder chaussee, a major highway that ran along the southern edge of berlin. . to reach the target beneath schonefelder chaussee, the tunnel needed to be about 1,500 feet long, roughly as long as five football fields. engineers figured that a six-foot-high tunnel of that length would displace about three thousand tons of sandy soil.
–the dark game, paul janeczko

which word best describes the tone of the passage?
discouraged
impressed
curious
negative