I believe it's A) Change the comma to a semi-colon hope this helps :)
A likely indirect result of their tumultuous relationship is increased stress for their children.
If this couple fights a lot, it is going to affect their children as well because they will be living in a household where they are witnessing conflicts and the lack of love almost each day. They will be anxious all the time, which will then negatively affect their mental state, and thus their lives in general.
Answer:
Sergey had headache because she knocked her head against the wall.
E I believe I may be wrong, hope this helps.
