#feedback

I understand how I got the question wrong because I didn't understand the grammar of the question. My question is what are some tips for us to realize we are dealing with a bi-conditional ?

Hi, could you please explain how answer choice B is correct? I believed that B was incorrect because it made an assumption that the crime rate had stayed the same throughout the past 20 years. The stimulus says the crime rate didn't decrease, but it did not indicate in the stimulus whether it increased or stayed the same throughout the past 20 years.