Which is the correct Lewis dot structure of C2H2

The correct answer is A
The octet rule state that all main group elements form bonds such that they achieve a noble gas configuration with eight valence electrons. In this case carbon has 4 electrons in its outermost shell and requires 4 more electrons to achieve an octet. Hydrogen is an exception to the octet rule and it only requires two electrons to achieve an octet. All the other options have C and H forming bonds that do not lead to a noble gas configuration.