Which sentence uses a linking verb?

a.
they sat in the middle of the theatre.

b.
the robinsons went to see a movie.

c.
the theatre was empty when they arrived.

d.
they bought two large bags of popcorn

faithful servants eumaeus and philaetius:

his ragged vest then drawn aside disclosed the sign conspicuous, and the scar exposed: eager they view'd, with joy they stood amazed with tearful eyes o'er all their master gazed:

these servants know ulysses by the scar he got when he was a child - so when he showed them the mark, they immediately knew this is truly their master and they hugged him, finally starting to believe his words.