Rate of dehydrohalogenation (E2 elimination) - substrate structure effect

2023 Manipur 1 question

1. The correct order for the rate of $\alpha,\beta$-dehydrohalogenation for the following compounds is ____. (i) 1-iodopentane; (ii) 2-iodopentane; (iii) 2-iodo-2-methylbutane (tertiary halide) [add image]