The correct answer is B. M°L1T-1.
The coefficient of transmissibility is a dimensionless quantity that is used to describe the relationship between the input and output of a system. It is defined as the ratio of the output to the input, and it is typically expressed in decibels (dB).
The dimensions of the coefficient of transmissibility can be derived from its definition. The input to a system is a force, which has the dimensions of mass times acceleration (M·L/T2). The output of a system is a displacement, which has the dimensions of length (L). Therefore, the dimensions of the coefficient of transmissibility are M°L1T-1.
Option A is incorrect because it has the dimensions of mass (M). Option C is incorrect because it has the dimensions of length squared (L2). Option D is incorrect because it has the dimensions of mass times length cubed (M·L3).