The 1875 might be a "B"; that was the mark of the Hannover mint, shut down in 1878. But the 1910 can't be a "B".
The mintmarks on 5pf coins are pretty small; get a magnifier and check again. D or E are the most likely options for you.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis