For works with multiple authors, you may list the first author's name followed by which of the following that indicates there are multiple authors?
a. et all
b. and al.
c. et al.
d. et all.

The best and most correct answer among the choices provided by your question is the third choice or letter C. For works with multiple authors, you may list the first author's name followed by the word "et al.". 

Et al. is a Latin abbreviation that means 'and others'. It's used in place of names for the purpose of saving time and space when providing in-text citations.

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