please answer all questions :)

MULTIPLE CHOICE. Choose the ane alternative that best campletes the statement or answers the queation. 20) What is the IUPAC name of this compound? 20) A) 2-methyl-3-ethylhexane B) 3-ethyl-2-methylhexane C) 4-propylhexane D) 4-ethyl-5-methylheptane 21) What is the IUPAC name of this compound? 21) A) 3-ethyl-4-propylnonane B) 3,3-dimethyl-4-propylnonane C) 3,3-dimethyl-4-butylnonane D) 4-isopentylnonane