Which statement is true of equinoxes?

Days and nights are equal in length everywhere.

The sun’s vertical rays are striking either 23.5°S or 23.5°N.

The length of daylight in the Arctic and Antarctic circles is 24 hours.

They occur in June and December.

Whenever diploid populations are in hardy-weinberg equilibrium at a particular locus a) the allele's frequency should not change from one generation to the next, but its representation in homozygous and heterozygous genotypes may change. b) natural selection, gene flow, and genetic drift are acting equally to change an allele's frequency. c) this means that, at this locus, two alleles are present in equal proportions. d) the population itself is not evolving, but individuals within the population may be evolving.