You can use Pythagreos theorem to determine it!
Pythagreos theorem is a^2 + b^2 = c^2
1) 4^2 + 4^2 = 6^2
16 + 16 = 36
32 = 36 (So this is not a right-angled triangle )
2) 16^2 + 12^2 = 20^2
256 + 144 = 400
400 = 400 (Sp this is a right-ngled triangle)
The Given Triangle PMO is a Right Angled Triangle with m∠M = 90°
Given m∠P = 40°
We know that : Sum of Angles in a Triangle = 180°
⇒ m∠P + m∠M + m∠O = 180°
⇒ 40° + 90° + m∠O = 180°
⇒ 130° + m∠O = 180°
⇒ m∠O = 180° - 130°
⇒ m∠O = 50°
We can notice that m∠O and m∠1 form a Linear Pair (180°)
⇒ m∠O + m∠1 = 180°
⇒ 50° + m∠1 = 180°
⇒ m∠1 = 180° - 50°
⇒ m∠1 = 130°
Last Option is the Answer
There is 1 brother as they would all have the same brother.