The correct options are
(a) Solids have definite shape and definite volume.
Reason — In solids the inter-molecular space is the least and the molecules remain in their fixed positions due to strong inter-molecular force of attraction so solids have definite shape and definite volume.
(b) Liquids have definite volume but no definite shape.
Reason — The molecules in liquid are less closely packed, their positions are not fixed and they move freely. Although the inter-molecular force of attraction is weak as compared to solids but it is sufficient to keep them within the boundary of the vessel. So liquids have definite volume but no definite shape.