The correct answer is A. 99.10%.
According to the 2010-11 agricultural census, 99.10% of the holdings in Himachal Pradesh were small and marginal holdings. A small holding is one that has less than 2 hectares of land, while a marginal holding is one that has less than 1 hectare of land. The high percentage of small and marginal holdings in Himachal Pradesh is due to the fact that the state has a mountainous terrain, which makes it difficult to cultivate large areas of land.
Option B is incorrect because it is the percentage of small and marginal holdings in India as a whole. Option C is incorrect because it is the percentage of small and marginal holdings in the state of Uttar Pradesh. Option D is incorrect because it is the percentage of small and marginal holdings in the state of Madhya Pradesh.