At the time of the constitution was written, what three parts could not be amended?

Its either b or c   i'm leaning towards b though i've heard of them during that time period 

Jackson  said nullification 'means insurrection and war,' and called it a treasonous attack on america. the second aspect of the  force bill  was the passing in congress of a lower tariff in 1833. this was offered as a compromise to avoid conflict with south carolina, and to attempt to defuse the tense situation.source google