6459. Traffic being what it is, it is lamentable that our roads are unable to take the load.

✅ The correct answer is option B.
unpardonable : (of a fault or offence) too severe to be pardoned; unforgivable.

deplorable : shockingly bad in quality.

inexcusable : too bad to be justified or tolerated.

terrible : extremely bad or serious.

lamentable : (of an event, action, or attitude) unfortunate; regrettable.

Synonym of lamentable is deplorable