The correct answer is option 2: Displacement of rock strata has disturbed the arrangement of rocks and made it complex.

Option 1 states that the Himalayan region is made up of crystalline rocks. While this is true, it does not explain why the region is poor in mineral resources.

Option 3 suggests that the climatic conditions are not suitable for the exploration of minerals. While the Himalayan region does have challenging climatic conditions, such as harsh winters and heavy monsoons, this is not the main reason for the lack of mineral resources.

Option 4 states that the rugged terrain makes mineral exploration difficult and costly. This is partially true, as the Himalayas are characterized by steep slopes and difficult accessibility. However, it does not fully explain why the region is poor in mineral resources.

Option 2 accurately explains that the displacement of rock strata in the Himalayan region has disturbed the arrangement of rocks, making it complex. This geological complexity makes it difficult to find and extract mineral resources effectively.

In conclusion, the correct answer is option 2 because the displacement of rock strata in the Himalayan region has made the arrangement of rocks complex, thereby hindering the exploration and extraction of mineral resources.