Answer:
Part 1:
The four astronomical bodies one could choose to represent the 4 labels in the diagram are
A - universe
B - galaxy
C - solar system
D - Mars
The universe contains galaxies and galaxies holds solar systems which have planets like Mars
Part 2: D or a planet like Mars is unlike all their other astronomical bodies it does not have other astronomical bodies within it thus, its different from rest.
The correct answer is b, antigens
CLOUD FORMATION, he said it under the question but i put it here so it would be easier too find
