Step 1: Understanding the Concept:
This question requires knowledge of the characters and plot from a specific story in the prescribed curriculum, likely "The Artist" by Shiga Naoya.
Step 2: Detailed Explanation:
In the short story "The Artist", the main character is a young boy named Seibei. The story opens by describing Seibei, a twelve-year-old boy who is still in primary school and has a passion for collecting and polishing gourds. This detail is central to establishing his character and the conflict of the story.
Step 3: Final Answer:
The character who was twelve years old and still at primary school in the story is Seibei himself. Therefore, option (A) is correct.