Solution

Linnaeus is considered as the father of taxonomy. He classified the flowering plants based on the floral characters. The classification was based on the number of stamens and the basis of carpel characteristics. Since, his classification employed sexual characters, it is termed as sexual classification. The artificial system of classification is based on the observable characters such as habit, number, forms, the number of stamen which makes the classification system proposed by Linnaeus as an artificial system.
Thus, the correct answer is option D.