Consider this claim:

school uniforms should be mandatory for all students.

which statement gives the strongest evidence to support this claim?

according to the board of education, “school uniforms improve behavior, build school spirit, and develop a student’s sense of belonging.”
making school uniforms mandatory directly contradicts americans’ first amendment right to express themselves freely.
chris hammock, a mother of three high school students, said that mandatory school uniforms would make back-to-school shopping much easier.
recent reports indicate that school uniforms have a minimal impact on attendance rates in new york city public schools.

The correct answer is A. According to the board of education, “school uniforms improve behavior, build school spirit, and develop a student’s sense of belonging.”

Explanation:

A claim, which in this case is "School uniforms should be mandatory for all students" is a statement that expresses the position of someone regarding some topic, situation or issue. However, for any claim to be valid it requires reliable and relevant evidence such as facts, statistics or reference to external sources. In terms of effectiveness (how strong an evidence is) and reliability, which is whether a source can be trusted or not, expert's opinions, and research studies are preferred over informal ones such as examples, anecdotes or people's opinion.

Considering this, the statement that gives the strongest or more effective  evidence to support the claim about making school uniforms mandatory is "According to the board of education, 'school uniforms improve behavior, build school spirit, and develop a student’s sense of belonging' ” because this is part of a reliable source as this is an expert's opinion, also, this evidence directly supports the claim by showing the benefits of making uniforms mandatory and therefore is reliable and effective (strong).