Answer both thanks !!

16: D edit it ment to be d

17: B

Explanation:

For 16 if you look at the chart you can calculate by seeing what letters intersect which was D.

For 17 it's common sense if you do research.

the most common type of reef is the fringing reef. this type of reef grows seaward directly from the shore. they form borders along the shoreline and surrounding islands.