Answer:
C. Class
Step-by-step explanation:
A img tag allows you to put an image. An img tag is not a attribute.
a p tag allows you yo make a paragraph. A p tag is not an attrbute.
A class attribute allows you to give an element a specific class. Styling the class in css will style all elements which have the class.
A src tag is used for referencing script and style locations. It is an attribute but not the one we are looking for.
Thus, The answer is C, a class.