Step 1:
Rtusamhāra is a Khandakāvya, while Naişadhīya Carita is a Mahākāvya.
\[
A \rightarrow II,\quad B \rightarrow IV
\]
Step 2:
Mālavikāgnimitra is a Sanskrit drama (Nāţaka).
\[
C \rightarrow I
\]
Step 3:
Nitiśataka belongs to the Muktaka category.
\[
D \rightarrow III
\]
Step 4:
Hence, the correct sequence is:
\[
A-II,\; B-IV,\; C-I,\; D-III
\]
Therefore, the correct answer is:
\[
\boxed{\text{(4)}}
\]