We know there are 3 real estate companies looking to trade buildings with each other. The buildings are categorized as class 1, 2, or 3 depending on their value.
R S T
We're told that R has G (class 1), Y (class 3), and Z (class 3)
R
G1 Y3 Z3
S has F (class 1), and L (class 2)
S F1 L2
T has K, M, and O, and they're all class 2
T K2 M2 O2
Each trade has to be one of 3 kinds:
1) trading buildings of the same class (X for X)
2) trading 1 class 1 building for 2 class 2 buildings (1 - 22)
3) trading 1 class 2 building for 2 class 3 buildings (2 - 33)
R can trade with S and T, and S and T can trade with each other
If R and S trade, they could either trade F for G or L for Y and Z
If R and T trade, they could trade Y and Z for either K, M, or O, or they could trade G for two of K, M, and O
If S and T trade, they could trade F for two of K, M, or O or trade L for one of K, M, or O
We can think of the class 3 buildings as being worth 1, class 2 buildings as being worth 2 (since two class 3 buildings equal 1 class 2 building), and class 1 buildings as being worth 4 (since two class 2 buildings equal 1 class 1 building)
From this, we know that R, S, and T each have buildings that are collectively worth the same amount. Their properties are each worth 6, so after trades, R, S, and T must each have collective values of 6 since all trades are of equivalent value.
In looking at this question, we see that (C) says, "(C) RealProp: the Garza Tower and the Lynch Building Southco: the Flores Tower, the Yates House, and the Zimmer House Trustcorp: the King Building, the Meyer Building, and the Ortiz Building"
This is totally possible
R
G1 Y3 Z3
S F1 L2
T K2 M2 O2
If R and S trade Y and Z for L, then we would have the same buildings with the various companies that (C) has.
R
G1 L2
S
F1 Y3 Z3
T K2 M2 O2
Thus, (C) is the correct answer.
Hope this helps. Let us know if you have any more questions!