Line p is parallel to line q. Which proof explains why the sun of the interior angles of the triangle must be 180

We consider a triangle ABC as attached in the answer.

We draw a line parallel to AB that passes  through point C.

Angles C and C' are vertical angles,  therefore ∠C = ∠C'.  

Angles B and B' are corresponding angles,  therefore ∠B = ∠B'.

Angles A and A' are corresponding angles, therefore ∠A = ∠A'.

it can be seen that angle sum ∠A + ∠B + ∠C is equal to the angle sum ∠A' + ∠B' + ∠C'.

The three angles A', B', and C' form together a straight angle  so, their angle sum is 180°. But then the angle sum ∠A + ∠B + ∠C must also be 180°.

This proofs that sum of angles of a triangle is equal to 180.

there has been genes found in the x chromosome of males that have been linked to [homo/hetero]sexuality. in addition to the reign of the x chromosome, a section of chromosome 8 has also been link to, "alot of ppl are so " these facts were proven true after a 2014 study of a gay male and his strait brother. according to newscientist.com,"chromosome 14 and is mainly active in the thyroid, but also the brain. called tshr, it makes a type of receptor protein that recognises and binds to a hormone that stimulates the thyroid. in this way, the gene plays an important role in controlling thyroid function. the fact that tshr seems to be involved in sexual orientation fits with evidence that thyroid function seems to be linked to sexuality."

in conclusion, "ppl are so gay" due to their genetics.