Is this sentence active or passive: I said that it was OK.?

Active

You obviously do not know what passive means and until you do you will never get these questions right. Passive is when something is done to the subject and usually preceded by the verb to be e.g. he was killed. Every verb is either active or passive. When the subject is doing something it is active and when the subject is having something done to it it is passive.

All of them are active. All passive sentences should have a linking verb + past participle.

all of them are active... all passive sentences should have a linking verb + past participle...

passive, it has the word was

Active voice but with syntax error (because I is actually saying that it is no longer okay. Correct rhetorically by rewording thusly: I said that it is okay. (That way you don t have a voice in past tense referring to a past event which might have changed by the time present voice averred the earlier event.

All are active.

It's active voice. The main verb is "said."

All three of the examples you posted are in active voice. The presence of "was" or "is" in the subordinate clause has nothing to do with it. @Celine is a moron.

passive, it has the word was