Which of the following is a tertiary alcohol?
a.) [tex]\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{OCH}_3[/tex]
b.) [tex]\left(\mathrm{CH}_3\right)_3 \mathrm{COH}[/tex]
c.) [tex]\left(\mathrm{CH}_3\right)_2 \mathrm{CHCOH}[/tex]
d.) [tex]\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{OH}[/tex]