A couplet consists of two consecutive lines of poetry that typically rhyme and have the same meter.
In the options you've provided, the lines are from William Shakespeare's Sonnet 116, and they are not arranged as couplets. However, the lines "But bears it out even to the edge of doom" (A) and "I never writ, nor no man ever loved" (B) can be interpreted as completing thoughts, with the other two options (C and D) also providing poetic assertions about love. None of these options specifically form a couplet in their current arrangement.
If you are looking for a specific couplet from the lines provided, none of them form a traditional rhyming couplet in pairs that would fit the typical definition.