Because it is not the actual word
The correct answer is C. past tense.
Past tense is a grammatical tense used to describe an action or event that is done in the past. "Mixed" has a regular form "mix" and by adding "-ed" to it, it becomes a past tense.
Answer:
he should weigh his options and choose a solution
The other 3 answer choices don't sound correct the answer is d.
Make sure you keep your reader interested, if its short make sure it makes sense. Maybe add a plot twist or a bad beginning and a great ending.