Which sentence is correct?
ted and i cannot convince steve to change, because he must first convince himself.
ted and i cannot convince steve to change, because he must first convince he himself.
ted and myself cannot convince steve to change, because he must first convince himself.

The sentence that is correct is letter a) Ted and I cannot convince Steve to change, because he must first convince himself.

Explanation:

The sentences provided in the question are using reflexive pronouns. A reflexive pronoun, as its name suggests, reflects the action back to the subject. That means the object and the subject of a verb are the same. Compare the sentences below:

- I cut the tree. --> I, the subject, performed the action of cutting. The tree, the object, "received" the action of being cut.

- I cut myself. --> I, the subject, performed the action of cutting. I also received the action of being cut, so I am also the object.

Knowing that, we can easily choose letter a as the best option. Steve must convince himself --> Steve is performing the action of convincing, as well as receiving it. He is not convincing anyone else; Steve is convincing Steve.

Letter b is wrong because there is no need to use the pronoun "he" right before the pronoun "himself." Letter c is wrong because it is employing a reflexive pronoun (myself) where there is no need for it, since no action is reflecting back at "me".

the answer is   b suffix addition