Detailed Instructions: In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.
Q: Article: Dr charlotte Uhlenbroek recently returned to London after filming her second series, Jungle. It was difficult, 19-week trip, during which she explored the rainforests of Borneo, the Amazon and Congo, travelling around using variety of means of transport, including hot-air balloons and canoes. "I'm interested in the way animals communicate with each other. It was sometimes dangerous making the program ---I even went swimming with piranha fish. But the worst thing was insects. On one occasion I had 70 sand-fly bites on my arm. Luckily I didn't get sick. I prefer not to take tablets every day, but if I get a fever, take some medicine immediately." Filming the series was exciting, but also frightening at times. Her most challenging experience was climbing a 100-meter tree in Borneo, as she has a great fear of heights. "I had to keep pulling myself further and further upwards. All I wanted to do was get down again. Suddenly the safety equipment didn't look very strong and I thought that my ropes would break and I would crash to the ground." What did she enjoy most about returning to London? "When I've been away in hot uncomfortable conditions for a long time I dream about an ice-cold drink and my bed at home! But the thing I look forward to the most is nice long showers. There wasn't much water in some of the places we visited and I worried that I was using it all up and not leaving any for my colleagues on the camera team! "
Answer: she hates being in high places
A:
Charlotte found climbing the tree in Borneo so frightening because _ .