Covariance will be + or - number near to zero. so C is correct if two variables are unrelated as one increase, the other shows no pattern and covariance will be a positive and negative number near to 0.
hopes this helps.
Use order of operations, or PEMDAS which stands for Parenthesis, Exponent, Division, Addition, and Subtraction.
Do those operations in that order. Can you try?
What will be the first thing you do here, according to PEMDAS?
When angles and sides are all equal