Highest point occurs in \(1946\)

At this point the total is slightly above \(120\) for convenience we can assume it as \(120\)

Now, to find Federal debt held by government we look at the black bar

It is slightly above the mid point of \(0\) and \(20\). At mid point it would be \(10\) since it is slightly above mid point let us assume it as \(12\).

Hence federal debt held by public would be \(120 -12 = 108\)

Therefore the ratio would be \(\frac{108}{12} = 9:1\)

approximately option D would be the closest.

_________________

This is my response to the question and may be incorrect. Feel free to rectify any mistakes