Question

Which of the below statements about the CMB are true?

(i) The “hot” and “cold” spots are areas where photons have slightly more or less energy than average.
(ii) It shows that the Universe was accelerating at the time the CMB formed, thus measuring dark
energy early in the Universe.
(iii) The “hot” and “cold” spots were caused by sound waves created from photon pressure because
of slight density variations. If inflation is true, these density variations are a result of quantum
fluctuations during inflation.
(iv) The CMB power spectrum gives information on the overall shape (geometry) of the Universe.

(a) (i), (ii), and (iii)
(b) (i) and (iii)
(c) (i), (iii), and (iv)
(d) (i), (ii), (iii), and (iv)