Scientists already knew earlier that wind and splashes of rainwater can move bacteria and other germs from leaf to leaf. 22 other possible transmission routes, researchers at Virginia Tech observed water drops on the leaves of wheat plants that were infected with leaf rust.
答案：(B) In a search for
【句型】in a search for 字詞搭配「為了尋找」，表示「為了尋找其他可能的傳播途徑」；As a result of（由於……的結果）、With a view to（為了，通常接動名詞，搭配不如in a search for自然）、To the extent of（到……的程度）都不合。
你比較熟的說法可能是 in search of（不加 a），例如 in search of food（覓食）。本題用的是 in a search for，兩種都成立——search 當可數名詞時可以加冠詞，後面配的介系詞就從 of 換成 for。整組的意思都是「為了尋找……」。
看前後兩句的關係。前一句：Scientists already knew earlier that wind and splashes of rainwater can move bacteria...（科學家早就知道風和雨滴會移動細菌）。本句：___ other possible transmission routes, researchers at Virginia Tech observed water drops...（___ 其他可能的傳播途徑，研究人員觀察了水滴）。已知的途徑之外還想找別的，所以做了觀察——空格填的是「做這個觀察的目的」。 other（其他的）這個字也在提示：這是在既有知識之外「另尋」新東西。
As a result of（由於……的結果）表原因，但「其他傳播途徑」是他們要找的目標，不是造成觀察的原因；With a view to 雖然也表目的，但它後面固定接名詞或動名詞、且語意偏「著眼於某個計畫」，用在這裡不如 in a search for 貼切；To the extent of（到……的程度）用來表示程度或範圍。
in search of sth（尋找……）、in a search for sth（為了尋找……）、search for sth（搜尋……）、as a result of（由於……的結果）、with a view to Ving（為了……）、transmission route（傳播途徑）。
When a person sneezes, the droplets can spread diseases. Now research shows that plants have a somewhat 21 problem. Plant diseases can also spread through tiny water drops that jump off leaves— a plant's version of a sneeze. Scientists already knew earlier that wind and splashes of rainwater can move bacteria and other germs from leaf to leaf.
22 other possible transmission routes, researchers at Virginia Tech observed water drops on the leaves of wheat plants that were infected with leaf rust. They found that the sick plants could "sneeze" and 23 tiny water drops filled with leaf rust germs, spreading the disease to neighboring plants. The researchers noticed that small drops of water on the wheat leaves would move to combine and form a larger drop. As they were moving, the energy of the droplets in motion would be released. This energy allowed the water 24 into the air, which looked just like sneezing!
However, not all plants can sneeze. The ability is 25 to those with leaves that are hydrophobic, or repel water—a special feature that forces the liquid to move away when the leaf is exposed to it.