Question

what helps determine the absolute age of sedimentary rock layers?
index fossils in the layers
igneous rock layers above or below
other sedimentary rock layers above or below
cross - cutting relationships

Explanation:

Index fossils help determine relative age, not absolute. Cross - cutting relationships and other sedimentary layers also help with relative age. Igneous rocks can be dated using radiometric dating (e.g., potassium - argon dating), and if they are above or below sedimentary layers, the age of the igneous rock can help bracket the age of the sedimentary layers (absolute age).

Answer:

Igneous rock layers above or below