A triangle must have all of its angles add up to equal 180. An acute triangle must have all of its angles to measure below 90 degrees. A 90 degree measure would make a right angle, and any measure above 90 degrees would make an obtuse angle.
a. 70 + 50 + 90 = 210
The angles add up to 210, which means that these angles cannot form a triangle.
b. 70, 80, 30 = 180
The angles add up to 180, which means that these angles form a triangle.
c. 25 + 25 + 130 = 180
The angles add up to 180, which means that these angles form a triangle. However, there is an angle measure of 130, which makes this triangle obtuse.
d. 45 + 45 + 90 = 180
The angles add up to 180, which means that these angles form a triangle. However, there is an angle measure of 90, which makes this triangle a right triangle.
The answer is B. 70,80,30, as these angles are all below 90 degrees, and they add up to 180.
