I would say C. because if the words are spelled wrong might not go along with the sentence so, you would be confused.
So 60 minutes are in the hour.
60x8=480.
There are 480 minutes in 8 hours.
The correct answer is b. The verb tenses shift.
This is because the tenses don't match, meaning that at first you have a present simple and then a past simple. In order for them to be consistent they should be in the same tense.
Would you show me a picture of your problem ?
