A Rod of Infinite Length Has a Charge Per Unit $\lambda$

Multiple Choice

A rod of infinite length has a charge per unit length of $\lambda$ (= q/l) . Gauss's law makes it easy to determine that the electric field strength at a perpendicular distance r from the rod is, in terms of k = (4 $\pi$$\isin$ ₀) ^-1,

A) k $\lambda$ /r²
B) k $\lambda$ /r
C) 4 $\pi$ k $\lambda$ /r
D) 2k $\lambda$ /r
E) zero