Causal Stories

Tom has a huge garden and loves flowers. He employed two gardeners who take care of the plants: Alex and Benni. Alex and Benni are very reliable and Tom is satisfied with their work. Nevertheless he wants to optimize the plant growth. He decides to let Alex and Benni fertilize his plants. The magazine recommends the use of the chemicals A X200R or B Y33R. However, Tom also read that it can damage plants when they are exposed to multiple different types of chemicals. Tom therefore decides that he only wants to use one fertilizer. He goes for A X200R. When Tom meets Alex in the garden shortly afterwards, he instructs him to buy the chemical A X200R and to use only this fertilizer. He also explicitly instructs him to tell Benni to only use A X200R. Alex volunteers to buy several bottles of this chemical for Benni and himself and to tell Benni about Tom's instruction. After a few weeks, Tom realizes that some of his plants are much prettier and bigger than before but some of his plants are dried up. He wonders whether the drying of his plants might have something to do with the fertilization. He wants to investigate this matter and talks to Alex and Benni. Alex immediately starts apologizing: "I am sorry! I completely forgot to tell Benni about the rule! I bought and used the chemical A X200R but Benni must have used something else because he did not know about the new rule." Benni tells Tom that Alex had not told him that they were only supposed to use A X200R. He explains: "I have used the fertilizer I previously used; it is called B Y33R!" Tom remembers that he had filled B Y33R in a green can - long before he had read about the chemicals in his magazine. He had never used it. So Benni must have accidentally, without knowing it, applied the chemical B Y33R, whereas only Alex applied A X200R. Tom realizes that the plants dried up in the flower beds on which both A X200R and B Y33R were applied by the gardeners.

Did Benni cause the plant to dry out?