In these questions, there are two statements followed by two conclusions A and B. You have to take the statements to be true even if they seem to be at variance from commonly know facts and then decide which of the conclusions logically follows.
All boys are rivers.
Some rivers are girls.
A. Some girls are boys.
B: Some boys are girls.
The correct option is C Neither A nor B follow
I. All boys are rivers [A-type]
II. Some rivers are girls. [I-type]
Middle term is not distributed, therefore no conclusion can be drawn.