By definition, an abstract class can be

a$.$ only a base class

c$.$ only a derived class

b$.$ a base class or a derived class

d$.$ a derived class if derived

from another abstract class

A try block must be used

a$.$ inside a special function

c$.$ in an if statement

b$.$ in a loop

d$.$ anywhere $($no restrictions$)$

To catch every exception, the catch statement must be of the form

a$.($catch $...)$

c$.($catch any$)$

b$.($catch all$)$

d$.($catch$)$

The implementation of a friend function

a$.$ requires the keyword friend

c$.$ is the same as a non$-$friend

b$.$ optionally uses the keyword

function

friend

d$.$ must be written in the class

implementation $(.$cpp$)$

For a recursive function, there can be

a$.$ only one base case

c$.$ any number of base cases

b$.$ only one base case for each

d$.$ only two base cases

non$-$base case