Answer: D. Flowchart.
Answer analysis: When discussing which option can intuitively represent the pattern of the algorithm, we need to consider the characteristics of each option and how they relate to the visual representation of the algorithm.
A. Structure diagram: A structure diagram is usually used to represent the overall architecture of a software system or the relationship between components, and is not specific to the detailed steps of an algorithm. It focuses more on the hierarchy of the system and the interaction between components rather than the flow of the algorithm.
B. Pseudocode: Pseudocode is a method of writing algorithms using grammatical rules similar to natural language and programming language. It is easy for humans to read and understand, but it is not an intuitive graphical representation, but a textual form.
C. Source code: Source code is code written directly in a programming language to implement an algorithm. It contains a complete implementation of the algorithm, but it is also not an intuitive graphical representation, and requires certain programming knowledge to understand.
D. Flowchart: A flowchart represents the logic and steps of an algorithm in a graphical way. It uses various graphic symbols (such as rectangles for processing steps, diamonds for decision points, etc.) to clearly show the flow and control structure of the algorithm. Flowcharts are intuitive and easy to understand, and can directly reflect the pattern of the algorithm.
E. Process analysis: Process analysis is a method of analyzing business processes or data processing processes. It may include various forms of representation, but it does not specifically refer to a certain intuitive graphical representation method, and it is not necessarily used directly to represent the algorithm pattern.
In summary, the option that can intuitively represent the algorithm pattern is D. Flowchart.
The flowchart clearly shows the algorithm's process and control structure in a graphical way, making the algorithm's logic and steps clear at a glance.