It's _____world of wonders, ______world where anything can happen.

B.a, a

不是特指。没错。

a

B

For me, I will choose "A".

You know "a" and " the" are articles.
In the second blanket, " the world" is a fixed phrase.

B 虽然选A的很有道理 但是B读上去感觉更自然 语感告诉我选B - -#

b