The condensed structural formula for 2,3-dimethylbutane would be which of the following?
a) CH₃-CH(CH₃)-CH₂-CH₃
b) CH₃-CH₂-CH(CH₃)-CH₃
c) CH₃-CH(CH₃)-CH(CH₃)-CH₃
d) CH₂=CH-CH₂-CH₂-CH₃