Assertion (A): A horizontal line and a vertical line always intersect at right angles.
Reason (R): The measure of a right angle is 90°.
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
Assertion (A) is true but Reason (R) is false.
Assertion (A) is false but Reason (R) is true.
Answer
Assertion (A) is true, because a horizontal line and a vertical line are perpendicular to each other and hence always intersect at right angles.
Reason (R) is true, because the measure of a right angle is indeed 90°.
Reason (R) only tells us the measure of a right angle. It does not explain why a horizontal line and a vertical line intersect at right angles. So Reason (R) is not the correct explanation of Assertion (A).
Hence, option 2 is the correct option.
Assertion (A): An angle whose measure is 360° is called a complete angle.
Reason (R): The angle at point is 360°.
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
Assertion (A) is true but Reason (R) is false.
Assertion (A) is false but Reason (R) is true.
Answer
Assertion (A) is true, because an angle whose measure is 360° is called a complete angle.
Reason (R) is true, because the total angle at a point is 360°.
Since the angle at a point is 360°, a ray making one complete rotation about that point traces an angle of 360°, and this is exactly why such an angle is called a complete angle. So Reason (R) is the correct explanation of Assertion (A).
Hence, option 1 is the correct option.