Hi there needing with the iupac names for these compounds

For A:
Your longest carbon chain is 5 so it's overall a pentane

you have 2 branchings on Carbon 2 and 4; and the branchings are methyl groups

so the name would be 2,3-dimethylpentane

Give me a little on B: It's giving me some trouble

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .