Look at the pairs of sentences and decide which one matches with the meaning given.

1
a His cousin who was born in Argentina is a teacher.
b His cousin, who was born in Argentina, is a teacher. He's got only one cousin.
2
a The windows, which overlooked the garden, were open.
b The windows which overlooked the garden were open. All of the windows were open.
3
a The students who took a test had a hard time.
b The students, who took a test, had a hard time. All the students had a hard time.
4
a The fans who came to the concert were wearing the official band t-shirts.
b The fans, who came to the concert, were wearing the official band t-shirts. Only some of the fans were wearing the official band t-shirts.