Which of these is true about the argument of z1⋅z2z_1 \cdot z_2z1⋅z2?
arg(z1⋅z2)=arg(z1)⋅arg(z2)\text{arg}(z_1 \cdot z_2) = \text{arg}(z_1) \cdot \text{arg}(z_2)arg(z1⋅z2)=arg(z1)⋅arg(z2)
arg(z1⋅z2)=arg(z1)−arg(z2)\text{arg}(z_1 \cdot z_2) = \text{arg}(z_1) - \text{arg}(z_2)arg(z1⋅z2)=arg(z1)−arg(z2)
arg(z1⋅z2)=arg(z1)/arg(z2)\text{arg}(z_1 \cdot z_2) = \text{arg}(z_1) / \text{arg}(z_2)arg(z1⋅z2)=arg(z1)/arg(z2)
arg(z1⋅z2)=arg(z1)+arg(z2)\text{arg}(z_1 \cdot z_2) = \text{arg}(z_1) + \text{arg}(z_2)arg(z1⋅z2)=arg(z1)+arg(z2)