SAT一道语法题A job directory and a job service centre that provid

因为provides的主语是a job service center,而is的主语是a job directory & a job service center.
这样分开来看可能会清楚一点：
A job directory
&
A job service center that provides information for students in need of employment
ARE
available through the school's guidance office.

provides 与that 搭配是正确的，
is 与 A job directory and a job service centre 搭配，因而是错的。