I'm guessing you mean in Photoshop so you would
1. click the ruler tool
2. drag it along the line you know is straight
3. on the options bar, click straighten
hope this helps :)
A membranophone, it's sort of in the name. A membranophone is any musical instrument that produces sound with a vibrating stretched membrane. An idiophone is somewhat similar and produces sound by vibrating when hit but does not use strings or membranes (the instrument as a whole vibrates).
Answer:
They developed the first mathematical system of painting perspective
I think it’s A because I remember learning about this but I’m not 100% sure so if it’s wrong sorry