The correct answers are b) and c).
Polar liquids are miscible in polar liquids. Nonpolar liquids are miscible in nonpolar liquids. LIKE DISSOLVES LIKE.
a) H₂O has polar O-H bonds. C₆H₁₂ has only nonpolar C-C and C-H bonds. These liquids are not miscible.
b) H₂O and C₂H₅OH both have polar O-H bonds. They are miscible.
c) C₆H₁₄ has only nonpolar C-C and C-H bonds. CS₂ has polar C-S bonds, but they point in opposite directions (S=C=S), so the bond dipoles cancel. CS₂ is nonpolar. The liquids are miscible.
d). CCl₄ has polar C-Cl bonds, but they point to the corners of a regular tetrahedron. The bond dipoles cancel, so CCl₄ is nonpolar. C₂H₅OH is polar. The liquids are not miscible.