Students attending schools with mandatory uniform policies experience less pressure than do students who must choose their wardrobes. This is because school uniforms allow students and their parents to save money and time. The financial investment in uniforms at the beginning of the school year is far more economical than the purchase of an entire wardrobe of designer clothes and trendy styles. Students who do not have to deliberate what to wear each morning are able to invest their time in more productive ways, such as studying for tests or finishing homework. Uniforms may stifle students’ self-expression, but there are many other ways to reveal one’s individuality at school.

Which revision would best strengthen the author’s main argument?

the omission of the author’s point of view
the addition of more general statements and ideas
the correction of spelling and punctuation errors
the inclusion of reputable sources and specific facts

"This is because school uniforms allow students and their parents to save money and time." - A school uniform can cost more money than "normal" clothing. Perphaps a direct number would be good here (the average cost of a uniform vs the average cost of the equivalent amount in normal clothing). The next sentence could tie into this depending on what you were to find statistically.

"Uniforms may stifle students’ self-expression, but there are many other ways to reveal one’s individuality at school." - Mentioning a specific example of where a student has or students have expressed individuality would be helpful here.