Final answer:
A strongly metamorphosed rock with narrow foliation is gneiss.
Step-by-step explanation:
A strongly metamorphosed rock with narrow foliation is gneiss. Gneiss is a high-grade, foliated metamorphic rock that has alternating bands or stripes of light and dark minerals. It forms through intense metamorphism of schists or granites. Examples of other metamorphic rocks include schist, slate, and marble.