Cathy needs to collect linear data which set of data should cathy collect a. the height of a building for 20 years. b. the height of a person from birth till 20 c. the height of a tree for 20 years. d. the height of an elephant for 20 years.

Option A is correct.

Cathy needs to collect linear data . She should collect the data of option A-The height of a building for 20 years.

Explanation:

Linear data is that data whose slope is always same. Here lets assume, initially the building had 2 floors. Each year 2 floors are added above the previous floors. So our coordinate will be (0,2) (1,4) (2,6) (3,8)  and so on.

So slope =

=

= =

So, here slope is 2 for all coordinates.

c) yes, because of asa or aas