The Pennsylvania Railroad's steam locomotive class D3 (formerly Class C pre-1895) comprised sixty-seven 4-4-0 locomotives intended for general passenger and freight service constructed at the railroad's own Altoona Works during 18691881.They were the third standardized class of locomotives on the railroad and the most numerous of the early standard types; they shared many parts with other standard classes.This design differed from the Class A (later D1) mainly in its smaller drivers for greater tractive effort for freight haulage. Given a list of categories: company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, what category does the paragraph belong to?
The answer to this question is:
Mean Of Transportation