Though Lisa is opposed to capital punishment, she is asked to give a speech in favor of it to conclude a class debate. In the context of insufficient justification, dissonance theory predicts that her true attitude will undergo the most change if she

Accepts to give speech without any incentives.

Explanation:

Insufficient justification, in terms of cognitive dissonance theory describes about a  person depending of internal cause for any behavior's explanation as any external factor causing such behavior does not exist. Treat or reward can be enough to make a person involve into behavior or avoid behavior

According to the question,Lisa can experience most possible change in behavior if she accepts to give speech without any incentives for favoring the capital punishment.She will involve into such behavior due to reward .