It is letter C: Continental crust is thicker than oceanic crust.
This is an incomplete question, here is a complete question.
The conversion of cyclopropane to propene occurs with a first-order rate constant of 2.42 × 10⁻² hr⁻¹. How long will it take for the concentration of cyclopropane to decrease from an initial concentration 0.080 mol/L to 0.053 mol/L?
Answer : The time taken will be, 17.0 hr
Explanation :
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = 
t = time passed by the sample = ?
a = initial concentration of the reactant = 0.080 M
a - x = concentration left = 0.053 M
Now put all the given values in above equation, we get


Therefore, the time taken will be, 17.0 hr
1 Cellular Respiration
2 Photosynthesis
3 Photosynthesis
4 Cellular respiration
The balanced chemical formula should be Al2(SO4)3 + 6NaOH = 2Al(OH)3 + 3Na2SO4
Therefore the coefficient of Al(OH)3 is 2!
Hope that helps :)