(D) No,the statements do not mean the same thing as they provide different levels of information regarding the harvest.
$(a)$ This statement only provides the total quantity of the yield ($10$ quintals of wheat) without specifying the area or the time taken.
$(b)$ This statement provides the total quantity ($10$ quintals) and the area of land ($1$ acre) used for cultivation,indicating the yield per unit area.
$(c)$ This statement provides the most complete information: the total quantity ($10$ quintals),the area ($1$ acre),and the duration of the crop cycle ($6$ months). This reflects the productivity of the artificial ecosystem (the crop field) over a specific time period,accounting for both biotic components (wheat plants) and abiotic factors (water,soil nutrients,sunlight,and air) managed by the farmer.