Atriangle is reflected across line l and then line m. if the lines intersect, what kind of isometry is this composition of reflections? a-translation b- rotation c-reflection d- glide reflection

The Triangle is reflected across two lines.

 A composition means two or more transformation has taken place.

When the composition of two reflections between Intersecting line takes place, we consider it as equivalent to Rotation.

An Isometry means neither the change in shape,size, nor Angles (Interior as well as Exterior), that is two shapes after transformation are Congruent.

This kind of Isometry which is composition of reflections is called  

 Option D: Glide reflection