This is from part of a text in an English learners’ textbook published in Japan.
I am Shusei Yamada, a photojournalist. I drove around the world with an eco-friendly car named “Vasco-5.” The car runs on vegetable oil. It carries a machine which makes biodiesel fuel. That machine can make used vegetable oil into biodiesel fuel. There were two purposes of this adventure. One purpose was to examine how far I could go with only waste oil. The other purpose was to communicate with people around the world about biodiesel fuel. Before beginning my journey, I was worried about one thing. I was not sure that Vasco-5 could use all kinds of vegetable oils in the world. But some people say the only way to learn is “by doing.” So, I started my journey in Tokyo on December 5th, 2007. My first city was Vancouver, Canada. I asked for waste oil in many places. At first, my requests were often refused. That was because people did not know about biodiesel fuel. I was very disappointed. However, after people heard about my project, they started bringing me waste oil. A month later, I left for the US. Many people helped me on mu journey. Some people sent e-mails to their friends about my project. They were waiting for me with waste oil.
What does “They” in bold in the extract refer to? Some people or their friends? Both seem to be correct. If the word refers to Some people, it means they sent e-mails and waited for the man with waste oil for him. On the other hand, if it refers to their friends, it means they were waiting for him with waste oil because they received e-mails from their friends (i.e. “Some people” in the extract).
Which do you think is more correct?