The Maxwell's four equations are written as:

(i) $\oint \vec{E} . \vec{ds}=\frac{q_0}{\varepsilon_0}$
(ii) $\oint \vec{B} . \vec{ds}=0$
(iii) $\oint \vec{E} . \vec{dl}=\frac{d}{dt} \oint \vec{B} . \vec{ds}$
(iv) $\oint \vec{B} . \vec{d s}=\mu_0 \varepsilon_0 \frac{d}{d t} \oint \vec{E} . \vec{d s}$

Which of the above Maxwell's equations shows that electric field lines do not form closed loops?

(i) only

$\oint \vec{E} . \vec{ds}=\frac{q_0}{\varepsilon_0}$represents electric flux which is equal to the number of electric field lines crossing through an area.