Can someone explain to me how I can get the formula for K2S2O3?

Although the diagram is not shown, i know that the convection is heated by a the core.

Chewy,wrapped,not in all white,the wrapper is clear

The answer is the first option just took the test

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .