Please answer the following question: Pick one category for the following text. The options are - company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work. PKP class Ok22 -  PKP class Ok22 is a class of ordinary passenger (O) 4-6-0 (k) steam locomotive designed in 1922 forPolskie Koleje Państwowe (Polish State Railways PKP). It was the first locomotive designed in Poland after World War I so the design work was done jointly with Hanomag based on the Prussian P 8 (PKP class Ok1)
A:
Mean Of Transportation