Which option are correct for part 1, 2, 3, and 4? Thank you

In a study of parents 'perceptions of the size of their children's size, researchers (Kaufman et Biology, 2013) asked parents to estimate their youngest child's height.The Researchers hypothesized that parents tend to underestimate their youngest child's size because the youngest child is baby of the family and everyone else is that the family appears bigger compared to the baby. The sample of 39 parents who were surveyed underestimated their youngest child's height by 7.50 cm, on average; the standard deviation for the difference in actual heights and estimated heights was 7.20 cm and the data are not strongly skewed.

Part 1

Which of the following is an appropriate null hypothesis for this study?

1) Parents tend to underestimate their youngest child's height, on average.

2) Parents estimate of their young child's height is accurate, on average.

3) Parents tend to overestimate their youngest child's height, on average.

4) parents' estimate their younger child's height is inaccurate, on average.

Part 2

Which of the following is an appropriate alternative hypothesis for this study?

1) Parents' estimate of their youngest child's height is inaccurate, on average.

2) Parents' estimate of their youngest child's height is accurate, on average.

3) Parents tend to underestimate their youngest child's height, on average.

4) Parents tend to overestimate their youngest child's height, on average.

Part 3

Identify the observational units in this study.

1) Actual heights

2) Parents

3) Children

Part 3

Identify the parameter in this study.

1) The probability that parents will underestimate their youngest child's height,

2) The average child's height guessed by the parent,

3) The average amount by which parents' guess of their youngest child's height will differ from the actual height,

4) The probability that parents will overestimate their youngest child's height,

5) The probability that parents will correctly estimate their youngest child's height,