Final answer:
The statement that the writer can only buy the book herself is true.
Step-by-step explanation:
In order to find ideas for her research project on water management, the writer finds a book called Thirsty Planet: Strategies for Sustainable Water Management on Amazon.
However, when she goes to her college's library, she finds that the book is not available on the library shelves. Therefore, her only option is to buy the book herself from Amazon.
So, the statement that she can only buy the book herself is true.