Directions : Read the following passages and choose the best answers to the questions.
     In 1845, Captain Franklin, a British Royal Navy officer, took two ships and 129 men towards the Northwest Territories in an attempt to map the Northwest Passage, a route that would allow sailors to travel from the Atlantic to the Pacific via the icy Arctic circle.
     Stocked with provisions that could last for seven years, and outfitted with the latest technology and experienced men, the two ships –the HMS Erebus and the HMS Terror – were some of the biggest, strongest vessels ever to make the journey.
     But the men vanished into the frozen Arctic, leaving a few clues but no explanation as to what went wrong.
     The first search party set off 3 years later in 1848, In the latest hunt for the remains of Captain Sir John Franklin and his men, 160 years after he took his crew deep into the Arctic, representatives from Parks Canada announced the results from their search during the summer proved unsuccessful.

In the third paragraph, what does the phrase “what went wrong” (paragraph 3) refer to?