The correct answer is C. The door slammed shut because the wind will be blowing.
Step-by-step explanation:
In grammar, inappropriate shift in verb tense occurs when the main tense (present, future or past) is changed unexpectedly, and without a proper context or reason. For example, if you change the tense from present to the future even if you are still describing actions that happen in the present.
This occurs in the case of "The door slammed shut because the wind will be blowing" because the actions occur almost at the same time as due to the wind the door slammed shut. Due to this, it is necessary both to be in past " The door slammed shut because the wind was blowing" and it is incorrect to change the tense from past to future which means there is an inappropriate shift in verb tense.