The central idea contained in each paragraph should be limited to one.

Explanation:
When writing a paragraph, it is important to have a clear and focused central idea. The central idea is the main point or topic of the paragraph, and it helps to guide the reader's understanding and interpretation of the information presented.

Limiting the central idea to one allows for a concise and focused paragraph. It ensures that the information is presented in a clear and organized manner, making it easier for the reader to follow and comprehend. Having multiple central ideas within a single paragraph can lead to confusion and a lack of coherence in the writing.

By limiting the central idea to one, the writer can effectively develop and support that idea with relevant evidence and examples. This helps to strengthen the overall argument or message being conveyed in the paragraph. It also allows for a more efficient and effective communication of information to the reader.

Additionally, limiting the central idea to one makes it easier for the reader to identify and understand the main point of the paragraph. This can be especially helpful when skimming or scanning a text for specific information. It allows the reader to quickly locate the relevant information without getting lost in a sea of multiple ideas within a single paragraph.

In conclusion, limiting the central idea to one in each paragraph helps to ensure clarity, coherence, and effective communication of information. It allows for a focused and organized presentation of ideas, making it easier for the reader to understand and engage with the text.