Final answer:
Under surface pressure and temperature conditions, alkanes are the hydrocarbons most likely to form liquids and solids.
Step-by-step explanation:
Under surface pressure and temperature conditions, liquids and solids can be formed from aliphatic hydrocarbons. Aliphatic hydrocarbons include alkanes, alkenes, alkynes, and cyclic hydrocarbons that are not aromatic. Among these options, alkanes (choice a) are the most likely hydrocarbons to form liquids and solids as they are saturated hydrocarbons with only single covalent bonds.