You probably want to use kmeans.
Since you didn't give us any data to workj with, nor did you give us any idea of the number of groups, I've deciced to make some up.
Age = randn(40,1)*5+45;
C = 2*Age+100+20*randn(40,1);
This roughly replicates your data. Now I'll divide it up into 3 groups, and plot them with different colours.
idx = kmeans([Age,C],3);
cmap = parula(3);
clf; hold on
k = find(idx==i);
plot(Age(k), C(k), 's', 'MarkerFaceColor',cmap(i,:));
Feel free to play with the # of expected groups.