Please answer the following question: A professor began his class by holding up a glass with some water in it. He held it up for all to see and asked the students, " How much do you think this glass weighs?" "50 grams ! " "100 grams ! " "125 grams ! " the students answered. "I really don't know unless I weigh it , " said the professor, " but , my question is : What would happen if I held it up like this for a few minutes?" " Nothing , " the students said. "OK, what would happen if I held it up like this for an hour?" the professor asked. "Your arm would begin to ache, " said one of the students. "You are right, now what would happen if I held it up for a day?" "Your arm could go numb , and you might have to go to hospital, " another student said. "Very good ! But during all this, did the weight of the glass change?" asked the professor. "NO" "Then what made the arm ache and the muscle( ) stress?" The students were puzzled. " Put the glass down" said one of the students. "Exactly ! " said the professor. " Life's problems are something like this. Hold them for minutes in your head and they seem OK. Think of them for a long time and they begin to ache. Hold them even longer and they begin to trouble you. You will not be able to do anything. It's important to think of the problems in your life, but even more important to ' put them down' at the end of every day before you go to sleep. That way, you are not stressed; you wake up every day fresh and strong and can handle any issue, any challenge that comes your way ! " ,. Which of the following is true? A) The professor wanted to show the students how heavy the glass was. B) The weight of the glass would change if you held it longer. C) The glass itself made the arm ache and the muscle stress. D) The professor's arm would ache if he held the glass for a long time.
A:
D