SC from MGMAT CAT

[dippradhan]

Hogarth's engravings, which provide a vivid portrait of eighteenth-century London, are of interest to both artists and historians.
a)are of interest to both
b) are both interesting to

As per the answer explaination...
(b) "Are...interesting to" sounds casual compared to the preferred idiom.

Question(1)
I am not able to understand the term refered to "sounds casual comared" . Could you please help me.
Question(2)
"are of interest to both " -- do we have to make sure word "both" is close to one of the object it refers?

[tim]

the biggest problem is that b violates parallelism. take a closer look so you can see why..

[smohit04]

Here 'both' should refer to artists and historians, so a is right. But in b, 'both' is refering to Hogarth's engravings, which is wrong.

[jnelson0612]

Again, nice work smohit.