The correct answer is option 1, "The Earth is the densest of all the planets in our solar system". It means that the Earth has the highest mass per unit of volume among all the eight planets.

Let`s look at the other options:

Option 2 states that the predominant element in the Earth`s composition is silicon. While silicon does make up a significant proportion of the Earth`s crust, it is iron, not silicon, that is the most common element in the Earth as a whole.

Option 3 suggests that the Sun contains 75% of the mass of the solar system. In reality, the Sun accounts for about 99.86% of the mass of the solar system, so this statement is incorrect.

Option 4 says that the diameter of the Sun is 190 times that of the Earth, which is not accurate. The sun`s diameter is roughly 109 times the Earth`s diameter.