The algebraic sum of the resolved parts of a number of forces in a given direction is equal to the resolved part of their resultant in the same direction. This is known as

Answer: Option B

The algebraic sum of the resolved parts of a number of forces in a given direction is equal to the resolved part of their resultant in the same direction. This is known as the Principle of resolution of forces.

Here's the explanation:

The Principle of resolution of forces states that when you have multiple forces acting in different directions, you can break them down or resolve them into their individual components along a specific direction.
The algebraic sum (taking into account the signs of forces in that direction) of these resolved components will be equal to the resolved part of their resultant force in the same direction.
This principle is a fundamental concept in engineering mechanics and is often used to simplify the analysis of complex force systems.

So, the correct answer is Option B: Principle of resolution of forces.