Answer:
I wanted to do my homework alone.
Step-by-step explanation:
The sentence provided is-
____ wanted to do my homework alone.
Studying the sentence, we can know that the object of the sentence is homework. And this "homework" belongs to "my", which denotes the possession of the subject which will then be regarded as "I". So, using the subject "I" in the sentence, it makes complete sense that the homework had to be done "alone".
Thus, the best fit for the subject space in the sentence is
I wanted to do my homework alone.