The answer is D vertebrates <span />
Well,if you don't follow instructions you might make a mistake and mess up what you were supposed to do.Its making a cake,if you don't follow the instructions you could make the cake wrong and it would either not taste as good or it wouldn't come out like it should've.
When somebody puts " ing " at the end of a word (verbs) its become " happening " for example: watch- watching * present noun.
And to it's in future like I'm going to sleep it's when you are going to do it
Answer:
write an essay on the most interesting parts of your life
a. is the most reasonable. if i'm wrong srry.