Answer 4:
Seleucus is known to have at least 2 daughters: Laodice and Apama. The birthdate of these daughters is unkown, but following Ancient Greek tradition of naming the first born daughter after her grandmother and the second born after her mother, Laodice was probably the first born. The daughters had to have been born between 323-300 BC.
Seeing as the peace contract between Chandragupta and Seleucus Nicator took place between 305-303 BC, and following Ancient Greek tradition, the daughter should have been at least 15, but preferably between 16-18 for the marriage. This suggests that most likely it was the eldest daughter, Laodice, but it still could have been Apama if she was born before 319 BC.