A bag contains only red and blue marbles. If the probability of randomly selecting a red marble from the bag is 0.6, which of the following statements must be true?
There are more blue marbles than red marbles in the bag.
The probability of selecting a blue marble is 0.4.
There are exactly 6 red marbles in the bag.
If 10 marbles are selected, exactly 6 will be red.
