Which of these equations is the discretized form of the transient term using the first-order implicit Euler scheme?

( frac{( rho_C phi_C)^t+( rho_C phi_C)^{t+ Delta t}}{ Delta t} V_C+L( phi_C^t) )

( frac{( rho_C phi_C)^t-( rho_C phi_C)^{t+ Delta t}}{ Delta t} V_C+L( phi_C^t) )

( frac{( rho_C phi_C)^t-( rho_C phi_C)^{t- Delta t}}{ Delta t} V_C+L( phi_C^t) )

( frac{( rho_C phi_C)^t+( rho_C phi_C)^{t+ Delta t}}{ Delta t} V_C+L( phi_C^t) )

( frac{( rho_C phi_C)^t+( rho_C phi_C)^{t- Delta t}}{ Delta t} V_C+L( phi_C^t) )

Which of these equations is the discretized form of the transient term

1.	Which of these equations is the discretized form of the transient term using the first-order implicit Euler scheme?
A.	( frac{( rho_C phi_C)^t-( rho_C phi_C)^{t+ Delta t}}{ Delta t} V_C+L( phi_C^t) )
B.	( frac{( rho_C phi_C)^t-( rho_C phi_C)^{t- Delta t}}{ Delta t} V_C+L( phi_C^t) )
C.	( frac{( rho_C phi_C)^t+( rho_C phi_C)^{t+ Delta t}}{ Delta t} V_C+L( phi_C^t) )
D.	( frac{( rho_C phi_C)^t+( rho_C phi_C)^{t- Delta t}}{ Delta t} V_C+L( phi_C^t) )
Answer» C. ( frac{( rho_C phi_C)^t+( rho_C phi_C)^{t+ Delta t}}{ Delta t} V_C+L( phi_C^t) )