$1,5,14,30,55,91,?$ $,$ Find the missing term$.$

The correct option is B

$140$

In the given series $1,5,14,30,55,91,?$, we want to find out the missing term,

For that:

The pattern is $+4,+9,+16,+25,+36,\dots$

or $+2^2,+3^2,+4^2,+5^2,+6^2,\dots ..$

So in the next term we need to add $7^2=49$ to the preceding number.

i.e. $91+49=140$

Hence$,$ the next number is $140$

Therefore option $\left(B\right)$ is correct$.$