Step 1: Understanding the taxonomic hierarchy.
The highest taxonomic category in biological classification is the kingdom. It is the broadest classification, and organisms are grouped into one of the five kingdoms. Step 2: Analyzing the options. (A) species: Incorrect. Species is the lowest and most specific level of classification. (B) division: Incorrect. Division is a taxonomic rank used in plant classification, but it is not the highest category. (C) genus: Incorrect. Genus is a category above species, but it is not the highest. (D) kingdom: Correct. Kingdom is the highest taxonomic category in the biological classification system. Step 3: Conclusion.
The correct answer is (D) kingdom, as it is the highest taxonomic category.