Answer: A good Marriage
Step-by-step explanation:
A really nice car:can last for two years at least(not really lasting happiness)
A good marriage:Marriage is to spend your life with someone.Supposed to be happy and marriage is supposed to be for a long time.(most likely lasting happiness)
Winning the lottery:Winning the lottery can give you tons of money and you can save it.But will money buy lasting happiness?No.For some people,it can. But for this particular question,I would not recommend this answer.(maybe lasting happiness)
Getting Straight A's in school:Getting A's in school are good but they wont actually bring you real happiness. Happiness mostly has to do in personal life,not school. For some people,it can bring lasting happiness.But for you to have A's as your lasting happiness,then you strive have to have A's all the time.
This is just really my opinion,hope this helped :)