Aspecific type of physical change is a change.
a. chemical
b. bond
c. size
d. phase
i think it`s d. but i`m not sure.

C Size
A change of size in any object is a physical change. So, a specific type of physical change is a SIZE change.

A specific type of physical change is a change

D. phase

Example of Phase change is changing from Solid to liquid and Liquid to gas.

It is a physical change because the chemical nature of the compound involved is still the same. There is no introduction of new elements into the compound.

There is no reason to think the results are biased or not conducted properly but you should not assume the results are correct just because they were done in a laboratory so the answer would be c. it is likely to be reliable because the results support the conclusion presented.