Suppose "a" is an abstract class, "b" is a concrete subclass of "a," and both "a" and "b" have a no-arg constructor. Which of the following is correct?
a) Abstract class "a" cannot have a no-arg constructor.
b) Concrete subclass "b" cannot have a no-arg constructor.
c) Both abstract class "a" and concrete subclass "b" can have a no-arg constructor.
d) Neither abstract class "a" nor concrete subclass "b" can have a no-arg constructor.
