Chapter 25.3, Problem 25.4CE

Which of the following expressions are correct forms of Gauss’s law?

a. ${\Phi }_E={\displaystyle \oint \stackrel{\to }{E}\cdot d\stackrel{\to }{A}}$

b. $q_{\text{in}}={\epsilon }_0{\displaystyle \oint \stackrel{\to }{E}\cdot d\stackrel{\to }{A}}$

c. ${\displaystyle \oint \stackrel{\to }{E}\cdot d\stackrel{\to }{A}}=4\pi k{q}_{\text{in}}$