Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: When you squeeze one end of a tube to get toothpaste out from the other end, Pascal's principle is observed.
Reason R: A change in the pressure applied to an enclosed incompressible fluid is transmitted undiminished to every portion of the fluid and to the walls of its container.

Assertion A: When you squeeze one end of a tube to get toothpaste out from the other end, Pascal's principle is observed.

This is correct. The pressure applied at one end is transmitted through the toothpaste (which behaves approximately as a fluid) to the other end, pushing it out.

Reason R: A change in the pressure applied to an enclosed incompressible fluid is transmitted undiminished to every portion of the fluid and to the walls of its container.

This is correct. This is the statement of Pascal's law/principle.

R correctly explains A: the toothpaste comes out because the pressure applied by squeezing is transmitted undiminished throughout the enclosed paste (acting as a fluid), which is exactly Pascal's principle.

The correct answer is Both A and R are correct and R is the correct explanation of A.