Which layer of Earth is composed primarily of iron and nickel? (a) The core, (b) The crust, (c) The asthenophere, (d) The mantle, (e) The lithosphere.

Step 1: Define the Problem

Identify which layer of Earth is primarily composed of iron and nickel.

Step 2: Break Down the Problem

Examine each option to determine its composition:

• (a) The core
• (b) The crust
• (c) The asthenosphere
• (d) The mantle
• (e) The lithosphere

Step 3: Apply Relevant Concepts

Understand the composition of Earth's layers:

• The core is known to be composed mainly of iron and nickel.
• The crust is primarily composed of silicate rocks.
• The asthenosphere is part of the upper mantle, composed of semi-fluid rock.
• The mantle is composed of silicate minerals.
• The lithosphere includes the crust and the uppermost mantle.

Step 4: Analysis, Verify and Summarize

Analyze the composition of each layer:

• The core is the only layer primarily composed of iron and nickel.

Final Answer

(a) The core