sat 文法上一道语法题

题目

sat 文法上一道语法题
Citizens of Virginia cater their pets( as is evidenced by its )water bowls and doggie parks present throughout the neighbourhood.
a.as is evidenced by their
b.as evident in
请问为什么答案是b不是a呢

答案

their是指pets‘ 还是citizens’呢?指代不清,然后b更简洁.
as is evidenced by sth 和as evident in一样用法,但是形容词结构优先于动词结构