In natural convection heat transfer, the parameter is the
choose the right answer
a) nusselt number
b) rayleigh number
c) grashof number
d) lewis number

correct option is c

Explanation:

The Grashof number is a dimensionless number, which is named after renowned scientist  Franz Grashof. The Grashof quantity is defined as the proportion of the buoyant force to viscous force performing on a fluid in a pace boundary layer.

Its function in natural convection is more or less the same as that of Reynolds's number in compelled convection.

what is the question here. i think you messed up.