In △PAT,∠P=36∘,∠A=56∘, and PA=10. Points U and G lie on sides TP and TA, respectively, so that PU=AG=1. Let M and N be the midpoints of segments PA and UG, respectively. What is the degree measure of the acute angle formed by lines MN and PA?<spanclass=′latex−bold′>(A)</span>76<spanclass=′latex−bold′>(B)</span>77<spanclass=′latex−bold′>(C)</span>78<spanclass=′latex−bold′>(D)</span>79<spanclass=′latex−bold′>(E)</span>80