Correct Answer: Department 5

Solution : Variation in strength of employees in 2021 in comparison to that in 2020:
The number of employees in department 1 in the year 2020 = $\frac{24}{100}\times 1200 = 288 $
The number of employees in department 2 in the year 2020 = $\frac{21}{100}\times 1200 = 252$
The number of employees in department 3 in the year 2020 = $\frac{20}{100}\times 1200 = 240$
The number of employees in department 4 in the year 2020 = $\frac{19}{100}\times 1200 = 228$
The number of employees in department 5 in the year 2020 = $\frac{16}{100}\times 1200 = 192$
The number of employees in department 1 in the year 2022 = $\frac{21}{100}\times 1600 =336$
The number of employees in department 2 in the year 2022 = $\frac{22}{100}\times 1600 =352$
The number of employees in department 3 in the year 2022 = $\frac{18}{100}\times 1600 =288$
The number of employees in department 4 in the year 2022 = $\frac{19}{100}\times 1600 =304$
The number of employees in department 5 in the year 2022 = $\frac{20}{100}\times 1600 =320$
The variation in the strength of employees in 2021 in comparison to that in 2020.
In department 1 = 336 – 288 = 48
In department 2 = 352 – 252 = 100
In department 3 = 288 – 240 = 28
In department 4 = 304 – 228 = 76
In department 5 = 320 – 192 = 128
​​​​​​​Hence, the correct answer is Department 5.