PLEASE HELP ASAP!! WILL GIVE BRAINLIEST :) Latvia, Belarus, and Ukraine have what exports in common?

Below is a description of a resource that you're considering using for a research paper. as you read the description, keep in mind what you've learned about historical thinking skills and use those skills in evaluating whether or not to use the source.

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.

What does the term mandate” mean in terms of civil rights and liberties?