A bag contains 5 balls of unknown colours. There are equal chances that out of these five balls, there may be 0 or 1 or 2 or 3 or 4 or 5 red balls. A ball is taken out from the bag at random and is found to be red. The probability that it is the only red ball in the bag is

• A

  $\frac{1}{5}$
• B

  $\frac{1}{6}$
• Correct answer
  C

  $\frac{1}{15}$
• D

  $\frac{1}{30}$

Hence, the correct answer is option: 'C'.