To solve this problem, we need to analyze the given statements:$\newline$Assertion (A): A person goes to high altitude and experiences ‘altitude sickness’ with symptoms like breathing difficulty and heart palpitations.$\newline$Reason (R): Due to low atmospheric pressure at high altitude, the body does not get sufficient oxygen.$\newline$Let's break down each statement:$\newline \bullet$Assertion (A):$\newline$ - At high altitudes, the atmospheric pressure is lower than at sea level.$\newline$ - This results in a lower partial pressure of oxygen, leading to less oxygen being available for the body.$\newline$ - As a result, people may experience altitude sickness, which includes symptoms like difficulty in breathing and heart palpitations.$\newline$ - Hence, Assertion (A) is correct.$\newline \bullet$Reason (R):$\newline$ - The reason correctly states that low atmospheric pressure at high altitudes results in insufficient oxygen availability.$\newline$ - This is because the reduced pressure decreases the amount of oxygen that can be absorbed into the bloodstream.$\newline$ - Hence, Reason (R) is correct.$\newline$Now, let's determine if (R) is the correct explanation of (A):$\newline \bullet$The reason directly explains why altitude sickness occurs, as it highlights the lack of sufficient oxygen due to low atmospheric pressure.$\newline$Therefore, (R) is indeed the correct explanation of (A).$\newline$Thus, the most appropriate answer is Option 1: Both (A) and (R) are true and (R) is the correct explanation of (A).