What was the outcome of the testing of the all-steel prototype subway car numbered 3342 in 1904?

A. It was deemed too light for practical use and required additional weight to be added
B. It was found to have excessive vibration, poor insulation, and loud noise as previously feared
C. It was deemed too heavy for practical use but proved that an all-steel car could be feasible
D. It was completely rejected and never used again
Answer: 