Final answer:
In the morphological species concept, the important factors are size, shape, and structural features of organisms (e) a, b, and c, which are used to define and classify species.
Step-by-step explanation:
Under the morphological species concept, species are defined by morphological (physical) characteristics. This includes factors such as size, shape, and structural features of organisms. In this context, the reproductive strategy is not considered a defining feature. Instead, organisms are categorized based on observable physical traits, with the assumption that the more similar they look, the closer they are related in terms of species.
To answer the student's specific question, the important factors in the morphological species concept are a) size, b) shape, and c) structural features. Therefore, the correct answer is e) a, b, and c. These physical characteristics are used to classify organisms into species, based on the premise that similarity in morphology often indicates genetic closeness, hence the same species.