Which of the following are advantages of the use of panel data over pure cross-sectional or pure time-series modelling?

(i) The use of panel data can increase the number of degrees of freedom and therefore the power of tests

(ii) The use of panel data allows the average value of the dependent variable to vary either cross-sectionally or over time or both

(iii) The use of panel data enables the researcher allows the estimated relationship between the independent and dependent variables to vary either cross-sectionally or over time or both
(A)(i) only (B)(i) and (ii) only (C)(ii) only (D)(i), (ii), and (iii)
B