Between Which of These Amino Acid Pairs Might a Hydrophobic

Question

Between which of these amino acid pairs might a hydrophobic interaction occur?
A)Ser/Ile
B)Val/Leu
C)Tyr/Cys
D)His/Val

Accepted Answer

Both Valine and Leucine are hydrophobic amino acids and can interact through hydrophobic interactions. The other options have either one or both polar/charged amino acids making it unlikely for a hydrophobic interaction to occur.