Correct the underlined part with the appropriate phrasal verb:
The antique vase fell apart as she threw it on the floor in a rage.
  (A) NO CHANGE
   (B) fell down
   (C) fell together
   (D) fall apart

Hint: A complete sentence is correct only if you are applying grammar rules correctly. A phrasal verb is a verb that is formed by the main verb with an adverb or a preposition, or both phrasal verb’s meaning is not actually from the meaning of the individual words.

Complete answer:
In the above question, we are talking about phrasal verbs.
Let’s understand the phrasal verb by an example- He has always looked down on me.
In this example, the phrasal verb ‘to look down on someone’ doesn't mean that he is looking down from the height at someone who is below to him.It means that he thinks that he is better than you.
The underlined part in the above sentence is a phrasal verb of the form verb(fell) and adverb(apart) which means ‘ broke into pieces or parts’ here reference is a vase that broke when it fell. It is the correct phrase and does not require any change.
Fell down is a phrasal verb that means ‘to fail, unsuccessful’ or the action of falling down. It is not required as in the question it is mentioned that the vase fell on the floor, So, option(B) is incorrect.
Option(C) ‘Fell together’ means ‘to be merged, to be close’, this doesn't refer to the breaking of the vase. Therefore option(C) is incorrect.
Option (D) ‘Fall apart’ is in the present tense and the given sentence is in the past tense we can see by the verb ‘threw’ which is in the past tense. So, option(D) is incorrect.

Note:
 In English grammar rules should be applied correctly. A phrasal verb is a verb that is formed by the main verb with an adverb or a preposition, or both phrasal verb’s meaning is not actually from the meaning of the individual words.’Fell apart’ is the correct phrasal verb in the sentence. So, the correct answer is option (A): NO CHANGE
The antique vase fell apart as she threw it on the floor in a rage.