The answer on that ? is B but I do not agree with that answer in the rule book rule 8section b 1a an obstructed runner may not be called out between the bases where obstructed unless appealed for missing a base so why is the answer B, please explain

The key to understanding this question (at least it satisfied me) is "R1 would not have made it home had obstruction not occured." If you have R1 protected, in your judgement, protected to where?

The phrase "may not be called out between the bases where obstructed" does not mean must advance.

The answer is "B" because when R1 (obstructed runner) is put out, the ball becomes dead. When there is a dead ball, all baserunners must be permitted to fulfill their baserunning duties prior to acknowledging any appeals. Since R1 is standing on 3rd, it would be a bit ludicrous to accept an appeal for a runner missing the base to which they have legally advanced and is standing upon.