Which newspaper headline sounds the least credible?

a. "scientist discover new species of kookaburra"

b. " scientist eager to discover more about new kookaburra species"

c. "previously undiscovered kookaburra species named"

d. "scientist go cuckoo for kookaburra"

The newspaper headline that sounds the least credible is  D. "Scientist go cuckoo for kookaburra."

Explanation:

Sentence  D. "Scientist go cuckoo for kookaburra" is the headline that sounds the least credible because it uses quite informal language, so it may be interpreted as unprofessional. The idea is that a headline should be specific, concise and compelling, but always taking into account the credibility and accuracy of the information one is sharing. Such an informal language would not be appropriate.

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