We know there are no large regions of antimatter near us because:

  1. antimatter is invisible
  2. antimatter is too heavy
  3. antimatter emits sound
  4. we don't see the gamma rays that would come from matter–antimatter annihilation at their boundaries
Answer

D) we don't see the gamma rays that would come from matter–antimatter annihilation at their boundaries

Absence of annihilation signals. SLO P-11-F-26 · Knowledge

Physics MCQ · More Nuclear and Particle Physics MCQs · Practise