Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: Iain Henderson has been tipped to spearhead Ireland's new breed of enforcers in the absence of key pack leaders Paul O'Connell, Peter O'Mahony and Sean O'Brien. Ireland will be forced to reshuffle almost half their pack for Sunday's World Cup quarter-final with Argentina at the Millennium Stadium, with O'Connell and O'Mahony out of the competition and O'Brien banned. Captain O'Connell's Test career is over after 108 caps, the 35-year-old set for hamstring surgery, while flanker O'Mahony needs an operation on torn knee ligaments. O'Brien has been banned for one match for punching France's Pascal Pape, leaving scrum coach Greg Feek backing bullish back-five forward Henderson to help fill the leadership void.Ireland face Argentina in Rugby World Cup quarter-final on SundayTheir pack is being reshuffled due to injury and suspensionCaptain Paul O'Connell, out for the tournament, is the biggest lossScrum coach Greg Feek has called on Iain Henderson to fill the void 
 Question:'Since coming back to the new laws, I think he has come back to the fore, and the _ has shown that if you don't get it quite right, anyone can hit you.

World Cup