What are functional groups?

What do the surveys of the three-dimensional distribution of groups of galaxies reveal about how groups ?

• What do the surveys of the three-dimensional distribution of groups of galaxies reveal about how groups and clusters of galaxies are organized? a. galaxy groups are distributed completely evenly--there is typically the same amount of space between them--and so there is no structure evident b. galaxy groups make a huge spiral structure that resembles the Milky Way (but is much bigger) c. galaxy groups are organized into huge spherical "lumps" with concentric rings of groups of galaxies around each lump d. galaxy groups are organized into huge filaments with great voids between them--something like the structure one would see taking a cross-section of some soap bubbles e. you can't fool me; astronomers cannot get any sense with our present-day instruments of how groups of galaxies are distributed on the large scale

• Answer:

  d