Answer:
The effect of the authors choice to tell the story Rescue Mission in the present tense is to create tension.
Step-by-step explanation:
By choosing to tell the story in the present tense, the author wants the reader to feel inside the story, to live vividly every situation described. The reader feels in a more intense way because he/she feels everything is happening while he/she reads it, in the present, so the feeling is he/she is living it and everything can happen.