You may solve this problem in two ways:
If you solve the inequality explicitly (divide both sides by 4), you get
[tex] \dfrac{4n}{4} < \dfrac{16}{4} \iff n < 4 [/tex]
So, if [tex] n [/tex] has to be stricktly less than 4, you can only choose 1, 2 and 3 as answers.
Alternatively, you can plug in all of the values you're proposed and check if the inequality holds:
If [tex] n=1 [/tex], you have [tex] 4<16 [/tex], which is true.
If [tex] n=2 [/tex], you have [tex] 8<16 [/tex], which is true.
If [tex] n=3 [/tex], you have [tex] 12<16 [/tex], which is true.
If [tex] n=4 [/tex], you have [tex] 16<16 [/tex], which is false.
So, again, only 1, 2 and 3 are solutions.
