Answer:
Thus, (1) is non parallel set and (2) and (3) are parallel set.
Step-by-step explanation:
Consider a triangle with vertices labeled as Q, R, S. Side QS is base. Sides RQ and RS contain midpoints M and N, respectively. A line segment is drawn from M to N as shown in figure below.
For MN and QS to be parallel the ratio of line segment must be in same ratio, that is
.
Check for the given options,
1) Given : QM=2, MR=4, SN=3, NR=5
Find the values in the ratio,


Thus, 
Thus, (1) is non parallel set.
2) Given : QM=2, MR=5, SN=6, NR=15
Find the values in the ratio,


Thus, 
Thus, (2) is parallel set.
3) Given: QM=2, MR=8, SN=3, NR=12
Find the values in the ratio,


Thus, 
Thus, (3) is parallel set.