The formation of block mountains are best associated with

Step 1: Analyze the question The question asks which process is best linked to the formation of block mountains (also called horst mountains).

Step 2: Explain the concept Block mountains form through faulting. When tensional forces (pulling apart) or compressional forces act on the crust, it cracks along fault lines. A block of land between two roughly parallel faults can be raised relative to the land on either side (or the surrounding land sinks). The raised block is called a horst, and the sunken area is a graben (rift valley).

Examples include the Ruwenzori Mountains (East Africa), the Black Forest and Vosges (Europe), and the Jos Plateau-type uplifted blocks in parts of Nigeria.

Step 3: Evaluate each option

• A. Accumulation of materials ejected from within the earth's crust: This describes volcanic mountains (e.g., Mount Cameroon), formed from lava and ash piling up. ✘
• B. Solidification of magma within the earth's crust: This describes intrusive igneous features such as batholiths and laccoliths. ✘
• C. Uplifting of crustal block within two parallel faults: This is exactly how a horst or block mountain forms. ✔
• D. Vertical movement of sediments into geosynclines: This relates to the formation of fold mountains, where sediments accumulate in geosynclines and are later compressed and folded. ✘

Step 4: Answer

Tip: Link each mountain type to its keyword:

• Block → Faults (horst and graben)
• Fold → Folding/Geosyncline
• Volcanic → Lava/Ejected materials
• Residual → Erosion

Whenever you see "faults" in an option, think block mountains.