Which is a complex sentence?

after you install the security software, your computer will run smoothly.

the technician installed my hard drive and turned on my computer.

my computer is lightweight, powerful, and portable.

both computers are powerful, but this one is less expensive.

both computers are powerful, but this one is less expensive.

I'm not 100% sure but I think this is the right answer. Hope this helps!

in "letter from a birmingham jail," king argues that there are four basic steps in any nonviolent campaign: "[c]ollection of the facts to determine whether injustices exist; negotiation; self purification; and direct action." finally, direct action is taken and acts such as boycotts and sit-ins are staged.

the anecdote makes readers feel sorry for the man’s lack of heritage, then reminds readers that the man has an equally valuable heritage.