Question

In which sentence is the adjective clause punctuated correctly

the poem, which was written in one night, tells a bleak story
the poem, that was written in one night tells a bleak story
the poem, tells which was written in one night tells a bleak story.
the poem tells a bleak story, which was written in one night

Answer 1

I believe it's the first one.

Answer 2

The poem, which was written in one night, tells a bleak story.

Here we have to keep in mind specific criteria, for the question is to determinate if the adjective clause results essential or nonessential.Anytime, you must decide if the adjective clause is essential or nonessential and then add or omit commas accordingly. Non Essential clauses do require commas.

Then, we move further to decide, according to these criteria, the need or absence of commas. IF written as... The poem tells a bleak story. The clause would turn to be nonessential since we could perfectly erase it and still the sentence could proceed. Whereas as a matter of fact the detail is then added (which was written in one night) and turns, therefore, to be nonessential.

Remember, to properly punctuate an adjective clause correctly. Added is an image to help: