Answer:
The correct answer is - option A. A difference in the cultural display rules.
Explanation:
Social or cultural displays rules are a social cluster or group and informal cultural norms to express their emotions in the correct way which are specific to cultural or social groups.
Pedro is an exchange student which makes his social norms different than the social norms or cultural display rules which cause difficulties to deal with the people and classmates.
I just translated this question, but I'll be giving you English answer so just translate it as well in your language.
In a residence with no basement, a dorm, or an apartment: Avoid windows. Go to the lowest floor, small core room (like a bathroom or closet), beneath a stairwell, or in an indoors hallway with no windows. Crouch as low as feasible to the floor, going through down; and cover your head with your hands.
The gravitational pull of the moon tugs on the surface of the ocean until its surface mounds up and outward in the direction of the moon.
Mutations result from an error in DNA replication, should it be from an alien source (like radiation) or simply a mistake in replication. Migration of organisms to a new population would alter the DNA by adding new genes, but it would not mutate them.