Please help me with this question, and explain!

For each of the following, indicate whether the expected relationship between the two variables will be positive (+), negative (-), or zero (0)

____ a. size of house and size of electric bill

____ b. height of parents and height of children

____ c. air humidity level and people's energy level

____ d. number of books read per year and age at which got first eyeglasses

____ e. hours spent at the beach and depth of tan