What makes a headline sound the most credible?

The correct answer is  formal language.

Explanation:

Good formal language is the best option to make a headline sound credible. This is the best resource for building trust in the audience and readers.

If we read a header with informal language, we will not trust 100% that the following text is really true.

A formal language leans more towards the academic or professional side, therefore the reader will intuit that it comes from a secure source.

Remember that a headline is the first look we have before reading any type of text and should emphasize the main action or the content that the audience will read. And to achieve this it is much easier to have read it with appropriate and academic language.

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