As stated in the other answer there is currently no way to determine suitable answers by only observing the limits.

Lets consider both rules you were shown in the lecture slides 64/107 and 76/107:

The first one checks for suitable variables, since we need to make sure that there is some "space" in which we can "move" our variable. Basicly our formula takes two things into account, first if our variable which harms its constraint is greater than the upper bownd (to large) or smaller than the lower bound (to small), and second it checks if the variable we want to swap with has some space in the corresponding direction. Therefore we need to consider the factor with which both variables relate. If our first variable is for example to large and our variable we want to swap with, is at its upper bound, then we are allowed to swap, if the factor which relates both variables is positive. This is because we could make the second variable smaller and as a result the first variable would also get smaller. If however the factor is negativ we are not allowed to swap, since we can not manipulate the second variable in a way that the first one will stay inside its bounds.

As can be seen here the factors which relate the bound and the unbound variables are important to find out pivoting partners and it is therefor not sufficient to only observe the bounds. If all the factors would be negative for example, each heuristic would need to be flipped.

Lets consider the second rule on page 76/107 (Blands rule):

To enforce termination we fix a variable ordering and always swap according to the variable ordering. It should be noted that usually we have (x_0 > x_1 > y_0 > y_1 > y_2), while we start with x_0 then x_1, followed by y_0 and so on. While it might be possible to find a more efficient method of determining potential pivoting partners, this might not lead to termination of the whole procedure.

**To recap: **As stated there is currently no way of "smartly" choosing variables, since this leads to a different set of problems, while at best this would be a heursitic, since the sign of the corresponging factor is important. In addition to that, for the exam you have to do the simplex algorithm as stated in the slides, which means you have to use the rules for finding pivoting partners stated on slide 64/107 and 76/107