Answer:
The best answer seems indeed to be: heroic quatrain.
Explanation:
Every time a poem presents an abab scheme, we can say it has alternate rhyme. But, in this particular question, the focus in the fact that the alternate rhyme happens within four lines. That is a characteristic of a heroic quatrain. A heroic quatrain or heroic stanza is comprised of four lines of alternate rhyme written in iambic pentameter - a pattern of five unstressed syllables followed by stressed ones.
