This is an odd question as it is not mentioned in the current iteration of the learning objectives. For many candidates, this question is simply solved by removing the incorrect options and seeing what you have left:

• "Anti-icing fluid has built up between the elevator and horizontal stabiliser."
  • This is actually possible, and in fact there have been quite a few reports over the years of rejected take-offs at rotation when the aircraft has failed to rotate correctly after de-icing. So much so that EASA commissioned a report to be made, testing de-icing fluid and its effects on a horizontal stabiliser section. The build-up of thickening fluids on the front of the elevator can make it very resistive to movements during take-off, especially with manual flight controls. Although it is not in the current learning objectives, it seems that an examiner wants you to know about it. Thankfully, it is the only possible correct option.
• "The control cables connecting the control column to the elevator have torn."
  • This would not be a case that is specific to icing conditions, and the cables tearing could cause a few different feelings on the control column, but most likely very light resistance to movement, not heavy. The aircraft also would not respond at all.
• "The ailerons have frozen in position."
  • The ailerons provide roll control, so whilst this is a bad situation, a pilot would not notice that the nose was heavy, as the pitch is controlled by the elevators.
• "The increased air density means insufficient thrust is being produced to reach V_R."
  • Quite the other way, high air density due to the cold air would cause higher thrust from the engine, and better performance.