True longitudinal analysis a. is concerned with the determination of cause-and-effect relationships. b. can be performed on any panel. c. involves a one-time cross-sectional sample of elements from the population of interest. d. can only be performed using panels that rely on repeated measurements of the same variables.

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step-by-step explanation:

so part 1: the y values stay the same, but the x values are opposite signs.

part 2 & 3: the line will be of equal lengths and will be straight.

part 4: you'd see the same characteristic because the x coordinate becomes a negative making them at equal distances from the y axis?

(a)   the cost of the fruit in $2 per lb = slope of the line

a cost of $10 ( the height of the vertical axis) and a weight of the strawberries ( the corresponding point on x axis)

so the lope   is   10/5 = 2   that is $2 per lb of strawberries

cost = 2w   where   w = weight of strawberries in pounds

(b) in the same   way cost of each lb of   blueberries = 10/7 =   $ 1.43

cost =   10w/7     where w = weight of blueberries in lbs.

c)     blueberries are cheaper ( $1.43 / lb against   %1 per lb for strawberries)

i tried my best if i'm right if i'm wrong i am so sorry.but if i am right plzzz mark brainliest: )