What is the basic formulae for calculating gross calorific value in bomb calorimeter?

• A. θ = [(W+w)(t2+t1)]/m
• B. θ = [(W-w)(t2-t1)]/m
• C. θ = [(W+w)(t2-t1)]/m
• D. θ = [(W+w)(t2+t1)]/m