A such question, while it is enough pacific that it proves definitively the priority of *Ev on both Luke and Matthew, is absent in Mark.
If artificially I place it in Mark, then even so I cannot raise the contradiction between a doubting John the Baptist and a baptized Jesus, since in Mark there is no trace of John the Baptist recognizing something of particularly divine/messanic in Jesus: indeed, the case has been made that John the Baptist didn't see the dove from heaven and didn't hear the voice from the heaven at the Jordan.
Hence, the baptism's scene in Mark would be ok with an hypothetical question “Are you the one who is to come, or should we expect someone else?” by John the Baptist introduced artificially in Mark.
Where the same question “Are you the one who is to come, or should we expect someone else?” would be in total contrast with Mark, is not with the baptism, but, which is the same, with the words of praise by Jesus addressed to John the Baptist:
And they asked him, “Why do the teachers of the law say that Elijah must come first?”
Jesus replied, “To be sure, Elijah does come first, and restores all things. Why then is it written that the Son of Man must suffer much and be rejected? But I tell you, Elijah has come, and they have done to him everything they wished, just as it is written about him.”
Jesus replied, “To be sure, Elijah does come first, and restores all things. Why then is it written that the Son of Man must suffer much and be rejected? But I tell you, Elijah has come, and they have done to him everything they wished, just as it is written about him.”
(Mark 9:11-13)
Therefore, by logical extension, also the baptism in Mark would be definitively in contrast with the question “Are you the one who is to come, or should we expect someone else?”, once the question is introduced artificially in Mark.
Therefore there are only two possible options:
- Mark knew about the question “Are you the one who is to come, or should we expect someone else?” and removed it under the urgent pression of the embarrassment.
- Mark didn't know nothing about the question “Are you the one who is to come, or should we expect someone else?” and it was *Ev that introduced it.