Read this run-on sentence.

We spent all day pulling weeds my back is sore.
Which of the following makes this sentence correct?

A) We spent all day pulling weeds; because my back is sore.

B) We spent all day pulling weeds, my back is sore.

C) We spent all day pulling weeds: my back is sore.

D) We spent all day pulling weeds, so my back is sore.