Two one-step diffusion processes have been conducted. Corresponding dopant concentration C and the junction depth xj changing with time t are plotted in Fig. (a) and fig. (b), respectively. Both plots are linearly scaled. According to the figures,
A、the process shown in Fig. (a) was a constant-surface-concentration diffusion. 
B、the process shown in Fig. (a) was a constant-total-dose diffusion.
C、the process shown in Fig. (b) was a constant-surface-concentration diffusion.
D、the process shown in Fig. (b) was a constant-total-dose diffusion.
E、both were constant-total-dose diffusion processes.
F、both were constant-total-dose diffusion processes.