Whichof the following statement is correct

A

$$ \triangle(U_k V_k) = U_k \triangle V_k + V_k \triangle U_k $$

B

$$ \triangle(U_k V_k) = U_{k + 1} \triangle V_k + V_{k + 1} \triangle U_k $$

C

$$ \triangle(U_k V_k) = V_{k + 1} \triangle U_k + U_k \triangle V_k $$

D

$$ \triangle(U_k V_k) = U_{k + 1} \triangle V_k + V_k \triangle U_k $$