Which of the following is/are an exception?
i) OutOfBoundException
ii) OutOfRangeException
iii) OverflowException
iv) UnderflowException
a) i)
b) i) and iii)
c) i) and ii)
d) i), ii), iii) and iv)

Answer: d
Explanation: The exception is thrown if a value is not a valid key. This represents errors that cannot be detected at compile time. OutOfBoundException, OutOfRangeException, OverflowException, UnderflowException are valid exceptions in PHP.