△ABC is a right angle at C and ∠A=20∘. If BD is the bisector of ∠ABC, then ∠BDC=
[asy]
size(200);
defaultpen(linewidth(0.8)+fontsize(11pt));
pair A= origin, B = 3 * dir(25), C = (B.x,0);
pair X = bisectorpoint(A,B,C), D = extension(B,X,A,C);
draw(B--A--C--B--D^^rightanglemark(A,C,B,4));
path g = anglemark(A,B,D,14);
path h = anglemark(D,B,C,14);
draw(g);
draw(h);
add(pathticks(g,1,0.11,6,6));
add(pathticks(h,1,0.11,6,6));
label("A",A,W);
label("B",B,NE);
label("C",C,E);
label("D",D,S);
label("20∘",A,8*dir(12.5));
[/asy]<spanclass=′latex−bold′>(A)</span>40∘<spanclass=′latex−bold′>(B)</span>45∘<spanclass=′latex−bold′>(C)</span>50∘<spanclass=′latex−bold′>(D)</span>55∘<spanclass=′latex−bold′>(E)</span>60∘