How should they improve their engagement rates with unengaged subscribers?

Northern Trail Outfitters (NTO) sends a hiking newsletter to an audience that has opted to receive messages about hiking. They have noticed in the last six months their open and click rates have been trending lower. NTO wants to reverse this trend.

How should they improve their engagement rates with unengaged subscribers?
A . Remove them from the list
B. Send emails more frequently
C. Request they resubscribe
D. Send emails less frequently

Answer: B