"The percentage of Covid-19 cases and the number of deaths" is a compound subject that is plural. Therefore, it requires a plural verb. The phrase "is reflection" should be replaced with "are reflective" to ensure subject-verb agreement.
The correct phrasing is: "are reflective of the level of spread". This maintains both subject-verb agreement and the proper use of adjectives. The other options do not correctly match the plural subject or use appropriate phrasing.
The correct answer is: "are reflective of the level of spread."