Fill in the blank with the most appropriate word.
A - Hello, what _________ your name?
A) is
B) are
C) am
D) be

Hint:
- Verbs are words that show action (sing), occurrence (develop), or state of being (exist).
- The above-given question is one of the most common self introductory questions where we need to fill the blank with the most suitable options.
- In general, the wh-word usually functions as the subject or object of the sentence.

Complete answer:
In non-functional linguistics, a sentence is a textual unit composed of one or more grammatically linked words. A sentence is a unit of written text delimited by graphological features such as upper case letters and markers such as periods, question marks, and exclamation marks in functional linguistics.

Let us analyze the given options:
Option A) is: The given sentence refers to the singular noun in the present tense. Therefore, “is” forms the appropriate word. Thus, Option A is the correct answer.
Option B) are: “are” is used with a plural noun, thus cannot be employed in the given sentence as the given question is in the present tense with the singular noun which demands a singular form. Hence, Option B is incorrect.
Option C) am: “am” is for the first person singular i.e, I am. As the first-person singular is missing in the above sentence thus, Option C is the incorrect answer.
Option D) be: "Be" is used to describe the identity, qualities, and condition of nouns. ‘‘Be” is not grammatically right to be used after what, hence, option D is also incorrect.

Therefore the correct answer is option ‘A’.

Note: Other self introductory sentences are How are you? Where are you from? etc.
The sentence is answered with My name is John and so on.. Usually, this is the first sentence that is spoken between strangers on greeting each other.