Correct option is B
The incorrect part is (B).
Detailed Analysis
- The Error: "...was slowly died, its..."
- The Problem: This is an error in verb form and voice.
- "Was died" is a passive construction, but "die" is an intransitive verb (a verb that does not take a direct object). Intransitive verbs cannot be used in the passive voice. You cannot "be died" by something else in this grammatical sense.
- The sentence describes a continuous process happening to the tree. Therefore, it requires the Past Continuous tense.
- The Correction: Change "died" to "dying."
- Corrected Sentence: The old tree in the backyard was slowly dying, its leaves turning brown...
Breakdown of Other Parts
- (A) The old tree in the: Correct. "The old tree" is the subject, and "in the" begins the prepositional phrase.
- (C) leaves turning brown: Correct. This is a participle phrase (an absolute construction) describing the state of the tree.
- (D) and branches becoming brittle: Correct. This maintains parallel structure with "leaves turning brown," using the present participle "becoming."
Grammar Guide: Intransitive Verbs and Passive Voice
A common mistake is trying to make a passive sentence out of a verb that happens naturally to the subject.