Which of the following sentences contains at least one error?

a$.$ Terry didn$$t consult the team before making a big decision because he was under pressure to provide a response to his boss quickly.

b$.$ I thought of a number of ways to work more efficiently and began working on incorporating them into my daily routine.

c$.$ Carmen could have taken the freeway to get there faster, but she was in no hurry and preferred the drive by the park.

d$.$ He should of rehearsed the speech several times before going on stage and delivering it to the entire department.