His disciples asked him
About the parables.”
Καὶ ὅτε εἰσῆλθεν εἰς οἶκον ἀπὸ τοῦ ὄχλου, ἐπηρώτων αὐτὸν οἱ μαθηταὶ αὐτοῦ τὴν παραβολήν.
This discussion is somewhat similar to a discussion that Peter had with Jesus in Matthew, chapter 15:15. Mark seems to indicate that the disciples had a lack of understanding. Mark said that when Jesus left the crowd (ἀπὸ τοῦ ὄχλου), he entered the house (Καὶ ὅτε εἰσῆλθεν εἰς οἶκον). Then his disciples were asking him about this parable (ἐπηρώτων αὐτὸν οἱ μαθηταὶ αὐτοῦ τὴν παραβολήν).