The correct answer is A. 25°.
A stair should not have a pitch more than 25°. This is because a stair with a pitch greater than 25° is considered to be too steep and can be difficult to climb. In fact, the American National Standards Institute (ANSI) has set a maximum pitch of 30° for residential stairs.
There are several reasons why a stair with a pitch greater than 25° is considered to be too steep. First, it can be difficult to climb a steep stair, especially for people with mobility issues. Second, a steep stair can be dangerous, as it can be easy to lose your balance and fall. Third, a steep stair can be uncomfortable to climb, as it can put a strain on your legs and back.
If you are considering installing a new stair, it is important to choose a stair with a pitch that is safe and comfortable to climb. A stair with a pitch of 25° or less is a good option for most people. However, if you have mobility issues, you may want to choose a stair with a pitch of 20° or less.
Here are some additional information about the other options:
- Option B: 30°. A stair with a pitch of 30° is considered to be too steep for most people. It can be difficult to climb and can be dangerous.
- Option C: 40°. A stair with a pitch of 40° is very steep and is considered to be dangerous. It is not recommended to install a stair with a pitch of 40°.
- Option D: 50°. A stair with a pitch of 50° is extremely steep and is considered to be very dangerous. It is not recommended to install a stair with a pitch of 50°.