In this question it is not mentioned whether ABC is a triangle, and it might be possible that angle ADB is less than 90 or more than 90.

BC/DC will be fixed more than 1

so the answer is D

can anyone please check??

I think this is a magoosh question ! They provide the answers to it ! Just click on view solution!

yes i found the solution, but in that they have considered angle ADB as 90. In question it is not mentioned that ABC is a triangle so I have a doubt.

if you look at point D they have drawn a little rectangle as a sign for <BDC, which means <BDC is a right angle or 90 degrees.

As, ADC is a straight line, <ADB is also a right angle.

yes agreed angle BDC is a right angle triangle, but it might possible that it is a quadrilateral.