My friend is not answering their phone. Either they are busy or there is something wrong. My friend always texts me when they will be busy and is not able to talk for a period of time. I didn't get a text from my friend so there must be something wrong. Which of the following is the best statement of the flaw in the argument above?

a. I always receive a text from my friend when they are busy.
b. Something is wrong because I didn't get a text from my friend.
c. My friend must be busy if they didn't send a text.