These 2 questions are actually the same. Q23 is from 2010 Pure Physics P1 while Q11 is from 2014 Sci Physics P1. Take a look at these 2 questions. If you are not sure, view the video below for the explanation.
Answer to Q23: Option A
Answer to Q11: Option D
If you do not know how to answer these 2 questions, view this video and also refer to the lens summary below.