Option 1 states that the Earth`s crust is composed of heterogeneous rocks. This means that the rocks in the crust are different in composition and characteristics. This statement is generally true. The Earth`s crust is made up of several types of rocks, such as igneous, sedimentary, and metamorphic rocks, which have different origins and properties.
Option 2 states that the central nucleus of the Earth is fluid. This statement is incorrect. The central nucleus, also known as the Earth`s core, is not fluid but rather solid. The Earth`s core is primarily composed of iron and nickel.
Option 3 states that below the crust, the material is wholly solid. This statement is generally true. Below the Earth`s crust lies the mantle, which is primarily made up of solid rock. The mantle is the thickest layer of the Earth and extends down to the Earth`s core.
Option 4 states that only option III is not true. This statement is incorrect because option III is true. The material below the Earth`s crust is indeed wholly solid.
In conclusion, the correct answer is option 2, as it incorrectly states that the central nucleus is fluid. Alert - the correct answer should be "Only I" because option 1 is not true.