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: A young mother is desperately trying to raise money for an expensive cancer treatment which could buy her more time with her family. Louisa Steckenreuter, 35, a mother to two young children, Darcy, 13, and Tilda, 2, was diagnosed with Osteosarcoma, a rare form of cancer last year. Now to have a chance at accessing potentially life-saving treatment the woman from Dulwich Hill, in Sydney's inner-west, needs to raise $100,000. 'What we’re hoping is that it gives me longer to spend time with my kids and watch them grow up. And grow old with husband like we had planned' Louisa Steckenreuter is desperately trying to raise money for an expensive cancer treatment which could buy her more time with her familyLouisa Steckenreuter was diagnosed with Osteosarcoma last JuneThe mother-of-two, 35, is fundraising to access expensive treatmentA drug called Keytruda could buy her more time with her husband and kidsIt costs $6000 a month and is not on the Pharmaceutical Benefits SchemeMs Steckenreuter would be the first Australian with her cancer to trial drug 
 Question:'Whereas the _ works with your body’s immune system and recognises the fact that the body’s immune system is able to fight the cancer cells if they realise the cells are bad,' Ms Steckenreuter explained.

Keytruda