Variables are words represented using lettters. Most words are represented using theor first lettter. According to the equation Given,

The varibles in the question are the dependent variblaes in the function and this are t, N, W and g.
o know which are variabkes, we will select the options that are starting with the variables.
t is the time
N is the Number of drinks
W is the Weight
g is the Gender
Hence the variables are:
Time
Gender
Weight and;
Number of drinks