For Loop plot and zeros function

Having problems with my for loop plot at the bottom of the code. I'm trying to plot the 3rd column in C2 for the different values of the paramater k2. I think the problem is in the way I use the zeros function. I set the number of rows as height of C1 which is just calculating the same thing but for one value of the parameter k2 so I assumed it would be the same for C2. I'm trying to plot C2(:,3) for each k2 value that is. Can someone please help?

clear all; close all;
clc
%Initial Concentrations
CA0 = 0.13;  %mol/L
CB0 = 0.1;  %mol/L
Qoa = 0.0005; %L/s
Qob = 0.0005; %L/s
Q1  = Qob + Qoa;
CA1 = Qoa*CA0/Q1; %mol/L
CB1 = Qob*CB0/Q1; %mol/L
CC1 = 0;
CD1 = 0;
initCon = [CA1, CB1, CC1, CD1];
V = 10*10^-3;
k2 = 1;
%Residence Time
tau = V/Q1;

% Volume
tauRange = [0,tau]; %s
%ODE SOLVER
[tauRange, C1] = ode45(@diffpfr, tauRange, initCon, [], k2);

%PLOT PFR
figure (1)
plot(tauRange, C1,'Linewidth',1)
grid on
xlabel('Residence Time [s]')
ylabel('concentration [mol/L]')
legend('C_A', 'C_B', 'C_C', 'C_D')

%YIELD PROFILE
CcCao = C1(:,3)./CA0;
figure (2)
plot(tauRange, CcCao,'Linewidth',0.5)
grid on
xlabel('t_e_n_d')
ylabel('C_C/C_A_0')

% YIELD PLOT for 3 ratios
k2s = [10, 5 , 1];
X = zeros(height(C1), length(k2s));
for i = 1:numel(k2s)
    [tauRange2, C2] = ode45(@diffpfr, tauRange, initCon, [], k2s(i));
    X(i) = C2(:,3);
end

[Najeem Afolabi]

Here's the function that I used

function dcdv = diffpfr(tau, C, k2)
    k1 = 100;
 
 %Rate Equations
 rA = -k1 * C(1)^2*C(2) - k2* C(1)*C(2);
 rB = rA;
 rC = k1 * C(1)^2*C(2);
 rD = k2* C(1)*C(2);
 
 %differential equations
 dcdv = [ rA;
          rB;
          rC;
         rD];
end

Answer 1

[Walter Roberson]

X(:, i) = C2(:,3);

[Najeem Afolabi]

Yes! Thank you very much had no idea why it wasn't working.