Which is one determinant of a health source’s credibility? a) the researchers ages b) the journaling length c) the date of publication d)the health topic

This would differentiate depending on who's reading the health source, but overall I believe anyone would believe more a longer source, so I would've to say the correct answer is B) The journaling length

How do we if it is a video and they know your face.

You did not show us the image of the burger, but i shall try to answer as best i can.  when purchasing food, always consider the ingredients as well as the person who prepared it. consider if they were hygienic people or not, in case the burger was infected with bacteria. no mortal should place an infected burger into their mouth.