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: Hollywood studio executives use it, as do, it's rumoured, a raft of A-list film stars who are desperate to roll back the years. Now clinics in the UK are reporting an influx of patients begging for the apparent elixir of youth — human growth hormone (HGH). Extraordinary claims are made for HGH. It gives you glossier hair, firmer skin, a greater sex drive, enhanced memory and more energy, say evangelists. Others use it for weight loss and muscle gain. Some say it can even make you look two decades younger. 'It seemed like magic,' says 40-year-old Aimi Veness, from East Sussex, who started using HGH last August. 'I was down to under 9st even though I was eating whatever I liked.Some say human growth hormone is an 'elixir of youth''Gives glossier hair, firmer skin, greater sex drive, enhanced memory'Others use it for weight loss and muscle gain - or to look youngerAimi Vaness, 40, from East Sussex, says 'it seemed like magic'But she's concerned HGH injections led to her getting lupus 
 Question:The global trade in _ is booming, with analysts estimating the market will be worth £2.4 billion by 2020.

HGH