Step 1: Identify the introductory clause.
Phrase (C):
\[
\text{``I have often made the point''}
\]
can naturally begin the sentence.
Step 2: Find the object clause.
Phrase (A):
\[
\text{``that true science fiction''}
\]
follows phrase (C).
Step 3: Complete the predicate.
Phrase (B):
\[
\text{``is a creation of''}
\]
comes next.
Step 4: Add the concluding phrase.
Phrase (D):
\[
\text{``the last two centuries''}
\]
completes the sentence.
Thus the sentence becomes:
I have often made the point that true science fiction is a creation of the last two centuries.
Hence the correct order is:
\[
(C),(A),(B),(D)
\]
\[
{\text{Option (B)}}
\]