[单选题]
The graph shows how the temperature oxdjd 0ic4zy++ b iera7;;r7g of 7gveyymfv .60p8s z/ta solid wax block varies with time. The solid wax has a specific heap 0g6yyf.zev vts87/ mt capacity of $2\,kJ\,kg^{−1}K^{−1}$ and it absorbs heat at a rate of 20W.
What is the specific latent heat of fusion of wax?
A. 50$J\,g^{-1}$
B. 100$J\,g^{-1}$
C. 200$J\,g^{-1}$
D. 400$J\,g^{-1}$