Which shows the correct use of a semicolon to combine sentences?
a. In 1876, Philadelphia held a world’s fair; Edmonia Lewis sent her sculpture to be exhibited there.
b. The city of Pompeii was built close to a volcano; when volcanoes erupt, they shoot ash into the sky.
c. French settlers first came to Canada in 1604; the weather was cold and it was hard to grow food.
d. In 1845, Frederick Douglass published his autobiography; it became a bestseller.