What's the field strength and pattern rules for bar magnets attached?

[pkc111]

TL;DR

What are the field strength and pattern rules for bar magnets attached to each other?

The attached probem tricked me because the answer is apparently D and not A.
Presumably because the magnetic field is weaker with 2 bar magnets joined N/S compared to a single bar magnet.
So this seems to be a gap in my knowledge as to the resulting strengths of magnets joined together. Are there any rules. I assume the magnetic strength is not 0 for the magnets in A, so what % loss will there be? What will the field lines look like? What if they were tied the other way N/N and S/S?
Many thanks

 

[anuttarasammyak]

Summary:: What are the field strength and pattern rules for bar magnets attached to each other?

What if they were tied the other way N/N and S/S?

Double current wrt D will be observed.

Zero current will be observed for A. Opposite induced currents by the opposite polar magnets cancel.