Answer:
The correct answer is:
Number of animals at the zoo.
Explanation:
" A lurking variable is a variable that explains the relationship between the two variables but it is not included as a response variable in the analysis and it can affect the interpretation of relationship between variables "
We know that the average amount of time spent on the zoo depends on the number of animals in the zoo because more the animals more will be the time spent to see all the animals.
Hence, the lurking variable is:
Number of animals at the zoo.