Guys help what’s the answer ?

According to the federal regulations, which of the following studies meets the definition of research with human subjects? a. a researcher uses the customs office’s passenger lists for ships bringing immigrants to the us between 1820-1845 to track the numbers of immigrants from certain ethnic groups.b. a researcher conducts a linguistic study of comments posted on a local public blog.c. a developmental psychologist videotapes interactions between groups of toddlers and their care givers to determine which intervention methods most effectively manage aggression.d. a researcher asks the director of a local free clinic about the number of patients in the last two years with newly diagnosed hiv/aids.

Mrs. walter’s husband died in 2016. she has not remarried and has maintained a home for herself and her dependent son, whom she can claim as a dependent. in the summer of 2018, the son was killed in an automobile accident. what is mrs. walter’s filing status for 2018

What is federalism? what is federalism