Two identical capacitors each of capacitance \( 5 \mu \mathrm{F} \)...

Two identical capacitors each of capacitance \( 5 \mu \mathrm{F} \) are charged to potentials \( 2 \mathrm{kV} \) and \( 1 \mathrm{kV} \), respectively. Their negative ends are connected together. When the positive ends are also connected together, the loss of energy of the system is:
a. \( 160 \mathrm{~J} \)
b. Zero
c. \( 5 \mathrm{~J} \)
d. \( 1.25 \mathrm{~J} \)