Answer:
D) Book.
Step-by-step explanation:
In academic writing, citations are an important part of producing an authentic and 'acceptable' work. And for this citation, be it for quotes or in listing the research source materials, several styles are accepted to be the correct way of citing sources.
In the given case, the citation goes like this-
Peet, Mal, Beck. Sommerville, Candlewick Press, 2017. Print.
This follows the Modern Language Association format of citing sources with the format "last name of the author, first name, name of the book. Place of publication, publisher's name, year of publication". Moreover, the inclusion of the word "print" means that it is in the printed or hardcopy form.
Thus, the correct answer is option D.