Answer:
a. Adult students are frequently motivated to return to school... (Alex, Marks, & Jones, 2005).
Step-by-step explanation:
It is important to consider that when information is paraphrased and you need to cite it, you have to include both the author/authors and the date such as in the example above. And although it is not a requirement, it is better to also include the number of the page from which the information was taken.