Read the extract given below and answer the questions that follow : (100-105)
O what is that sound which so thrills the ear
Down in the valley drumming, drumming ?
Only the scarlet soldiers, dear,
The soldiers coming.
O what is that light I see flashing so clear
Over the distance brightly, brightly ?
Only the sun on their weapons, dear,
As they step lightly.
O what are they doing with all that gear,
What are they doing this morning, this morning ?
Only the usual manoeuvres, dear,
Or perhaps a warning.
O why have they left the road down there,
Why are they suddenly wheeling, wheeling ?
Perhaps a change in the orders, dear,
Why are you kneeling ?

The poem has been written in the form of ...

The correct answer is a ballad.

Explanation and Analysis:

The given poem is W. H. Auden's poem titled "O What Is That Sound". It is structured in a dialogue format between two speakers (a dialogue between two lovers as soldiers approach).

A ballad is a form of verse, often a narrative set to music, characterized by:
1. Stanzas usually consisting of four lines (quatrains).
2. A distinctive rhythm, rhyme scheme, and often a conversational or dialogue-based narrative structure.
3. Themes frequently involving story-telling, mystery, warning, drama, or tragedy.

Looking at the features of the extract:
- It presents a narrative through a Q&A dialogue structure between two people.
- It follows a simple, repetitive quatrain structure with refrain-like repetition ("drumming, drumming", "brightly, brightly", "this morning, this morning", "wheeling, wheeling").

Therefore, the poem is written in the form of a ballad.