To solve this problem you must apply the proccedure shown below:
1. You must apply the formula for calculate the lateral area of a regular pyramid, which is:
LA=pl/2
Where "LA" is the lateral area of the square pyramid, "p" is the perimeter of the base of the square pymirad and "l" is the slant height.
2. You need to find the slant height, as below:
Tanα=opposite/adjacent
α=60°
opposite=l
adjacent=14 mm/2=7
Tan(60°)=l/6
l=7√3
3. By applying the formula, you have:
LA=(14 mmx4)(7√3)/2
LA=196√3
The answer is third option: 196√3.