Choose the correct one-word substitute for the given phrase.
A speech delivered without any preparation

Correct option is B

The correct one-word for the given group of words is (b) Extempore.
Extempore means spoken or performed without prior preparation or rehearsal. It refers to a speech delivered spontaneously, relying on the speaker's knowledge and presence of mind. (तात्कालिक, बिना पूर्व तैयारी के दिया गया भाषण)
Example:
The principal delivered an extempore speech after the chief guest was delayed.
Meanings of the given other options:
· (a) Lackadaisical: Showing little enthusiasm or determination; lazy or careless. (उदासीन, सुस्त)
· (c) Irascible: Easily angered or bad-tempered. (चिड़चिड़ा, शीघ्र क्रोधित होने वाला)
· (d) Mawkish: Overly sentimental in a weak or exaggerated way. (अत्यधिक भावुक)