A current source $I_s$ in parallel with a resistor $R$ is equivalent to a

a$.$ voltage source $V_s=I_{s}R$ in parallel with $R$

b$.$ voltage source $V_s=I_{s}R$ in series with $R$

c$.$ voltage source $V_s=\frac{I_s}{R}$ in parallel with $R$

d$.$ voltage source $V_s=\frac{I_s}{R}$ in series with $R$

A series voltage source $V_s=20V$ and resistor $R=4$ are equivalent to a

a$.$ voltage source $V_p=5V$ in parallel with $R=4$

b$.$ current source $I_s=5A$ in parallel with $R=4$

c$.$ voltage source $V_p=20V$ in parallel with $R=5$

d$.$ current source $I_s=20A$ in parallel with $R=4$

The following circuit yields nodal equation $$ and current $I=$

a$.(3+2+4)I_2-3(I_2-I_1)=12,2$

b$.\frac{V-12}{2}+\frac{V}{3}+\frac{V-12}{6}=0,8$

C$.\frac{V-12}{2}+\frac{V}{3}+\frac{V-12}{6}=0,2$

d$.\frac{V-12}{2}+\frac{V}{3}+\frac{V-12}{2}=0,8$