What is one way to ensure the validity of research sources?

Ensuring the validity of research sources is essential for establishing credibility and accuracy in any written work. Checking the publication date is a key aspect of this process because it helps determine the timeliness and relevance of the information presented. In many fields, particularly those related to science and technology, information can become outdated quickly. Therefore, a more recent publication date often indicates that the research reflects the latest findings and developments in that area. This practice helps researchers and writers provide accurate and current data, making their arguments more robust and persuasive.

The other options do not promote the validity of research sources. Using only online sources can lead to a reliance on potentially unverified or low-quality information. Limiting sources to popular articles may result in an oversimplified view of a topic, while ignoring the author's credentials could mean disregarding important qualifications that can affirm the reliability and trustworthiness of the information. Thus, checking the publication date stands out as a crucial method for ensuring research source validity.