Hey again, could you help me with this and explain? thank you

When are triangles considered similar? a. corresponding angles are equal andcorresponding sides are proportionalb. corresponding angles are proportional andcorresponding sides are equalc. corresponding angles are equal orcorresponding sides are proportionald. corresponding angles are proportional orcorresponding sides are equal select the best answer from the choices providedmark this and retumsave and exitnext

Non-euclidean geometry was discovered when, in seeking cleaner alternatives to the fifth postulate, it was found that the negation could also be true a. true b. false

Pls the last one and it has to be like number 6