Step 1: Understand the usage of tenses.
The sentence is talking about an ongoing situation that began two years ago. The appropriate tense to describe an action that was ongoing in the past and continues to the present is the past perfect continuous tense.
Step 2: Evaluate the alternatives.
"HAD BEEN BELONGING" is the correct choice as it uses the past perfect continuous tense. This tense is used when something was continuously happening before another action in the past. The sentence implies the house has been in possession for a period up to the present, indicating that it started in the past and is still true now.
"IS BELONGS" is grammatically incorrect and does not make sense.
"HAS BELONGED" suggests a completed action in the present and doesn't correctly convey the ongoing nature of the action over time.
"NO IMPROVEMENT" is incorrect because the tense used in the sentence is not suitable for expressing the ongoing action.
Step 3: Conclusion.
The correct phrase is "had been belonging," as it reflects an action that began in the past and continued until now, but we often use this construction for longer periods in English.