Question 18 is based on the passage you have just heard.

听力原文

        (16) [A new study carried out by the University of Lincoln has found a link between the personalities of cat owners and the behaviour and wellbeing of their cats.] The finding suggest that just as a parent’s personality can affect the personality of a child, the same is true for a cat and its owner. Owners defined as individuals with high levels of anxiety, fear, anger, depression, and loneliness were more likely to have cats with behavioural issues. Such cats displayed more aggressive and anxious behavioral styles as well as more stress related sickness. They were also more likely to have an ongoing medical condition and be overweight.

        The research also found that mentally well-adjusted owners had calmer, happier, and healthier cats. The researchers explained that many owners regard their pets as a family member and form close social bonds with them. (17) [The majority of owners want to provide the best care for their pets,] and it’s therefore possible that pets could be affected by the way their owners interact with and manage them. The study highlights an important relationship between our personalities and the wellbeing of our pets. (18) [Further research is needed to investigate the cause or nature of this relationship,] and to look at how owners’ personalities are directly influencing their pets behavior and wellbeing. It is possible that the wellbeing of pets is driven by the underlying nature of the owner, not simply by their conscious decisions and behaviors.

18. What does the passage say is still needed to understand the effects of owners personalities on their pets?

解析：D。录音中提到，需要进一步的研究（Further research is needed）来探查这种关系的原因或本质，这种关系指的就是上一句中主人的性格和宠物的健康之间的关系（relationship between our personalities and the wellbeing of our pets），即题干中的the effects of owners personalities on their pets。D项中的Further原词复现，investigation对应录音中的research，故为正确答案。

错项排除：A项的convincing、B项的extensive sampling和C项的more data在录音中都无依据，故均可排除。