Which statments are true about quadrilaterals

So, your answers are A). and C)., because for example, why are all squares rectangles?
*the reason being that a rectangle is just a stretched out square, and it still remains a parallelogram, as well as 4 straight sides.
All rectangles are parallelograms, no matter which side it is flipped on. It will also, have always 4 straight sides, which are pairs of parallel sides.
These facts are proven! :) Please if possible, please rate this answer as brainliest! Thank you!

Okay so for every triangle has three angles that always add up to 180 degrees. and to tell the difference between whether they are secure, right or obtuse is that acute: has one angle that is less than 90 degrees. right triangle means there is at least one angle that is exactly 90 degrees. and an obtuse angle has an angle that is bigger than 180 degrees. i’ll do #13 as an example: 13. 40 and 50 so if every triangle has 180 degrees 40+50= 90 degrees then180-90= 90 degrees so the third angle is 90 degrees and because this triangle has a 90 degree angle it means it is a right triangle