The correct option is B Unfenced, year 1
The fenced area exhibits numbers of thorns per plant in year 0 as compared to those found in plants of the unfenced area in the same year. In year 2, plants of fenced area exhibit the lesser number of thorns as compared to those found in plants of the unfenced area. The minimum number of thorns per plant is exhibited by unfenced area in year 2 while a maximum number of thorns per plants is exhibited by plants of the unfenced area in year 1. Thus, the correct answer is B.