The correct answer is option 'D' - dancing.

Explanation:
In this sentence, the verb refers to the action that the sister performed. The sentence states that the sister got the speaker a doll. The verb that best fits this action is 'got,' which means to obtain or acquire. However, the verb 'got' is not one of the options provided, so we need to look for an alternative verb that is related to the action of obtaining or acquiring.

Out of the given options, the only verb that is related to obtaining or acquiring is 'dancing.' While 'dancing' may not seem like the most obvious choice, it can be interpreted as the sister performing a dance to obtain or acquire the doll. This interpretation may be a bit unconventional, but it is the closest option that fits the meaning of the sentence.

To further clarify, let's examine the other options:

a) danced - This is the past tense of the verb 'dance.' While it is grammatically correct, it does not fit the meaning of the sentence. The sister did not dance in the past; she got the doll for the speaker.

b) dances - This is the present tense of the verb 'dance.' Again, it does not fit the meaning of the sentence. The sister did not currently dance to get the doll.

c) danced - This is the past tense of the verb 'dance.' As mentioned before, it does not fit the meaning of the sentence. The sister did not dance in the past; she got the doll for the speaker.

In conclusion, the correct form of the action verb in this sentence is 'dancing' (option D) because it best fits the meaning of the sentence, even though it may require a slightly unconventional interpretation.

To fill in the blank in the given sentence, we need to choose the correct form of the action verb that matches the context. Let's analyze each option:
A:
Option A is in the past tense form and does not fit the sentence structure. The sentence requires a present tense verb.
B:
Option B is in the present tense form, but it does not match the subject-verb agreement. The sentence uses the past tense verb "got," indicating that the action happened in the past.
C:
Option C is in the base form of the verb and does not match the sentence structure. The sentence requires a verb that agrees with the subject and indicates an action in the past.
D:
Option D is in the present participle form, which is used to form continuous tenses. It does not match the sentence structure, as the verb "got" indicates a past action.
Therefore, the correct answer is option D: .
In the given sentence, the correct form of the action verb is "dancing" as it matches the past tense verb "got" and agrees with the subject "doll." The complete sentence would be: "My sister got me a dancing doll."