Hey there,
The correct answer would be since and therefore. A cause and effect situation explains the reasoning for something happening. Examples:
(1. Since Johnny decided not to wear a coat outside, he got sick and therefore needed medicine.
(2. Since the cat was chasing the mouse for hours last night, he got tired and therefore napped all day.
Answer: Letter B ✅
Hope that helps! ★ If you have further questions about this question or need more help, feel free to comment below or post another question and send the link to me. -UnicornFudge aka Qamar