Read the excerpt from Princess Ida by Gilbert and Sullivan.
Women of Adamant, fair neophytes—
Who thirst for such instruction as we give,
Attend, while I unfold a parable.
The elephant is mightier than Man,
Yet Man subdues him. Why? The elephant
Is elephantine everywhere but here (tapping her forehead)
And Man, whose brain is to the elephant’s
As Woman’s brain to Man’s—(that’s rule of three),—
Conquers the foolish giant of the woods,
As Woman, in her turn, shall conquer Man.
This excerpt is an example of:.
a) blank verse.
b) free verse.
c) heroic couplet.
d) common meter.

a) Blank verse.

Explanation:

Blank verse is a form of poetry writing that has no specific rhyming sequence. It may be written in iambic pentameter, meaning ten syllables in a line but at times not all lines. The unstressed syllables are followed by the stressed syllables but they do not have any rhyming sequence.

In the lines from the poem given in the question, the lines do use iambic pentameter like-

Women of Adamant, fair neophytes—

Who thirst for such instruction as we give,

where the underlined words are the unstressed syllables while the ones in bold are the stressed syllables.

This un-rhyming verse form is also sometimes known as the heroic verse.

i would have to say "a" or "d".