Intrest rates and protective puts interest, something, purchase, exercise

AnalystForum

According to the text the purchase of a put protects bond investments from increases in interest rates. can anyone explain why?

A put option gives you the right to sell something. So if strike is 100 and price is 50 you exercise. if price is 150 you don't.

If interest rates rise, shouldn't it be disadvantageous to exercise at the higher rate?

i thinking I'm missing something but can't figure out what.

cheers