Consider the following statements:
(a) Plates are irregular-shaped slabs of solid rocks.
(b) Plates move horizontally over asthenosphere.
(c) Thickness of plates varies between 5-200 kms.
Choose the correct answer:

Question

Consider the following statements: 
(a) Plates are irregular-shaped slabs of solid rocks. 
(b) Plates move horizontally over asthenosphere. 
(c) Thickness of plates varies between 5-200 kms. 
Choose the correct answer:

Accepted Answer

Option 3, which states that (a), (b), and (c) are all correct, is indeed the correct answer. Here's why:

*   **(a) Plates are irregular-shaped slabs of solid rocks:** This statement is accurate. Tectonic plates are not perfectly shaped or uniform. They are composed of the Earth's lithosphere, which includes the crust and the uppermost part of the mantle, and they have varying shapes and sizes. They are essentially large, solid, and irregularly shaped pieces of rock.

*   **(b) Plates move horizontally over asthenosphere:** This statement is also correct. The asthenosphere is a highly viscous, mechanically weak and ductile region of the upper mantle. It lies below the lithosphere and allows the tectonic plates to move horizontally over it. This movement is driven by convection currents within the mantle.

*   **(c) Thickness of plates varies between 5-200 kms:** This statement is also accurate. Oceanic plates are generally thinner (around 5-100 km) than continental plates (which can be up to 200 km thick, especially under mountain ranges). The thickness varies depending on the age and composition of the plate.

Therefore, since all three statements are factually correct, Option 3, which includes all of them, is the correct answer.

Now, let's explain why the other options are incorrect:

*   **Option 1: Only (a):** This is incorrect because statements (b) and (c) are also true. Selecting only (a) would omit two other valid statements.

*   **Option 2: (a) and (b):** This is incorrect because statement (c) is also true. This option is incomplete as it doesn't include all the correct statements.

*   **Option 4: Only (c):** This is incorrect because statements (a) and (b) are also true. Selecting only (c) would omit two other valid statements.

In conclusion, Option 3 is the only option that accurately reflects the truth of all three statements, making it the correct answer.