Choose The best question for this sentence: $"$In Detroit daily newspapers are delivering their papers on only three days a week."

a$)$ What are daily newspapers doing in Detroit only three days a week?

b$)$ Where do daily newspapers are delivering their papers on only three days a week?

c$)$ How often daily newspapers are delivering their papers on in Detroit?

d$)$ Who are delivering their papers on only three days a week in Detroit?

e$)$ How many days a week do daily newspapers are delivering their papers on in Detroit?