Okay, did you have a conversation with one of the higher people in your school? If you're uncomfortable report it to the office.
The correct subject-verb agreement from the answer choices below is A)is...has.
'A cake or brownies is the easiest to serve. My mom has agreed to bake this weekend.'
That sounds better than
'A cake or brownies are the easiest to serve. My mom have agreed to bake this weekend.'
'A cake or brownies is the easiest to serve. My mom have agreed to bake this weekend.'
'A cake or brownies are the easiest to serve. My mom has agreed to bake this weekend.'
Those don't make sense when you read them, hence why A) is the correct choice.
C. Writing Skills
You need to be able to write, to be able to comprehend what you're reading
