In Which of the Following Situations Would a Random Sampling

In which of the following situations would a random sampling NOT be a reasonable approach to securing participants in research?

A) Dr. Jackson wants to study how undocumented workers who are fearful of deportation manage their worries about being arrested, so he plans on creating a list of all undocumented workers in this city and then selecting some of them at random, visiting them in person, and inviting them to participate.
B) Dr. Inge wants to observe workers who are striking, so she plans to visit a picket line and interview some of them chose at random.
C) Dr. Harrington wants to understand how the New York Times' reporting on immigration has changed over the last decade, so he plans to locate all articles on the topic that appeared in the paper in the last 10 years, and read and code a percentage of the total number of articles.
D) Dr. Griggs wants to analyze Pride parades in the U.S., so she makes a list of all cities that have such a parade, then chooses 20 cities to study using a random number generator.