It is true about Marcy's survey that she wants to study all visitors of the library and due to this, her sample is not representative.
Marcy's study focuses on determining the type of books that visitors prefer to borrow. Based on this, Marcy is studying the preferences of all the visitors to the library.
The sample selected is not representative because she is only considering those that go to the children's room on a specific day and time of the week rather than all the visitors.
Based on this, it can be concluded her population is all visitors and the sample is not representative.
Note: This question is incomplete because the options are missing; due to this, I answered it based on general knowledge.
Learn more about population in: https://brainly.com/question/905400