Petra walks into a brightly lit psychology lab to participate in an experiment involving the ability to perceive the colors of the rainbow. which photoreceptors will be most useful during this experiment?
a) conesb) foveac) lensd) rods

Which was not offically a state at the beginning of the civil war

According to the federal regulations, which of the following studies meets the definition of research with human subjects? a study of twenty 4th grade classrooms in which researchers ask the schools to systematically vary the time of day reading is taught, and collect weekly assessments of reading comprehension for each child over a three-month period.the collection of data, by a playground designer hired by the superintendent of schools, about the physical dimensions of school playgrounds, presence of fencing, and the kinds of equipment currently provided.a feasibility study for implementing a year-round school program, focusing on economic issues such a facilities utilization and transportation costs.an analysis of aggregate data comparing statewide high school graduation rates provided by the state department of public instruction, using county tax information.

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