Step 1: Solving OR (B):
1. Given \(\triangle ABC \sim \triangle PQR\), so \(AB/PQ = BC/QR = AC/PR\) and \(\angle A = \angle P, \angle B = \angle Q\).
2. Since M and N are medians, \(AB = 2AM\) and \(PQ = 2PN\).
3. Thus, \(2AM/2PN = AC/PR \implies AM/PN = AC/PR\).
4. In \(\triangle AMC\) and \(\triangle PNR\), \(AM/PN = AC/PR\) and \(\angle A = \angle P\). By SAS similarity, \(\triangle AMC \sim \triangle PNR\).
5. Similarly, \(MB/NQ = BC/QR\) and \(\angle B = \angle Q\), so \(\triangle CMB \sim \triangle RNQ\) by SAS.
Step 2: Final Answer (OR):
Similarities are proved using the ratio of medians being equal to the ratio of sides.