Question

A.
error: run-on sentence
space 1: insubordination
space 2: Ladybugs are helpful to farmers. Many use them in place of pesticides.
B.
error: comma splice
space 1: subordination
space 2: Ladybugs are helpful to farmers; many use them in place of pesticides.
C.
error: sentence fragment
space 1: rearranging/rewording
space 2: Ladybugs are helpful to farmers, so many use them in place of pesticides.
D.
error: run-on sentence
space 1: rearranging/rewording
space 2: Ladybugs are helpful to farmers. Many use them in place of pesticides.