I think its <span>Combine sentences 5 and 6 to create a long sentence.</span>
As for this problem concerning about a transition between sentences and paragraphs, the most probable and most likely to be the answer out of the options presented would be the third one which is a bridge.
A transition serves as a bridge between sentences and paragraphs. Though they create a divide between them, these transitions do not necessarily indicate that the divide is to cause to present that the two aren't connected to each other. A summary and introduction wouldn't do since a transition functions more and effectively between sentences and paragraphs.
Builds character and the second one is moves the story forwards
"We had passed through long walls of piled skeletons, with casks and puncheons intermingling, into the inmost recesses of the catacombs."
""We are below the river's bed. The drops of moisture trickle among the bones."
