Read the following context and choose the best option to answer the question.
Context: The telegraph operator explains that he 'll be glad to help her , then adds , " It 's just 99 cents a word . " Well , with only $ 1 left after paying for the bull , the brunette realizes that she 'll only be able to send her sister one word . After thinking for a few minutes , she nods , and says , " I want you to send her the word , ' comfortable . ' " The telegraph operator shakes his head .
Question: What is the reason the narrator sent the word " comfortable " ?
Options: 
- Because the plane ride was comfortable .
 - None of the above choices .
 - Her shoes are comfortable .
 - To reassure the sister .


To reassure the sister .