Two Identical Cylindrical Discs Have a Common Axis

Two identical cylindrical discs have a common axis.Initially one of the discs is spinning.When the two discs are brought into contact,they stick together.Which of the following is true?

A) The total kinetic energy and the total angular momentum are unchanged from their initial values.
B) Both the total kinetic energy and the total angular momentum are reduced to half of their original values.
C) The total angular momentum is unchanged,but the total kinetic energy is reduced to half its original value.
D) The total angular momentum is reduced to half its original value,but the total kinetic energy is unchanged.
E) The total angular momentum is unchanged,and the total kinetic energy is reduced to one-quarter of its original value.