Correct option is B
The correct option to fill in the blank is (b)
mean.
The sentence contains a double meaning usage of the word “mean” – once as an adjective for a person (cruel), and once as a mathematical term (average).
Since the second part “mean of first ten natural numbers is 5.5” clearly refers to arithmetic
mean, the only word that fits both blanks contextually is
mean.
Example:
He is a mean man who never helps anyone. /
The mean of 2, 4, and 6 is 4.
Other options:
· (a) clever: Smart or intelligent (चालाक)
· (c) honest: Truthful (ईमानदार)
· (d) shrewd: Sharp, cunning (चतुर/धूर्त)