Answer: d. casual order.
Explanation:
a.topical order : It means the main topic is divided into logical sub-topics. Hence, it is incorrect answer.
b.spatial order : In this type of speech, the main points follow a directional pattern. Hence, it is incorrect answer.
c.problem-solution order : In this type of representation, the first part involves stating the issues or the problems, & the second part revolves around providing the solution for the problems. Hence, it is incorrect answer.
d.causal order: In this type of speech representation, the cause and effects of a problem are looked upon. The approach is to discuss the effects first, and then discuss on the causes. Hence, it is the correct answer.