Aresearcher is exploring the effect of classroom environments on learning. two identical psy230 courses are being taught by the researcher. one is taught in a room with glass walls which allows students to see persons walking past, the other is in a similarly configured room with opaque walls. students' learning is assessed at the end of the semester with a comprehensive examination. the independent variable in this scenario is the:

Which is the best conclusion that can be drawn regarding the status of african-americans in the south in the late 1800s? a) african-americans made tremendous political, social, and economic advancements during the reconstruction era. b) passage of the 13th, 14th, and 15th amendments to the u.s. constitution guaranteed equal status and rights for all african-americans. c) the reconstruction policies enacted by the federal government were highly effective in african-american citizens transition to life after slavery. d) although african-americans had equal rights under federal law they were still economically, politically, and socially inferior to whites in the south during the reconstruction era.