Answer:
AB = 28cm
point C partitions AB into a ratio 1:3
they say to find the lengths of AC and CB
Usually in maths questions like this look at the order of things placed. Meaning…
ratio — 1:3
find — AC and CB
1 — AC
3 — CB
so now we know
1:3
AC:CB
1+3 = 4
28/4 = 7
7*1 = 7 = AC
7*3 = 21 = CB
Which (I believe) is the second option