Answer:
1.6 units
Step-by-step explanation:
Coordinates of A : (-1,1)
Coordinates of B : (3,2)
Coordinates of C :( -1,-1)
Now to find the length of the sides of the triangle we will use distance formula :

To find length of AB
A = 
B= 
Now substitute the values in the formula:





Now to find length of BC
B= 
C = 
Now substitute the values in the formula:





Now to find length of AC
A = 
C = 
Now substitute the values in the formula:




Thus the sides of triangle are of length 4.12, 5 and 2
Now to find area of triangle we will use heron's formula :
To calculate the area of given triangle we will use the heron's formula :
Where
a,b,c are the side lengths of triangle
a = 4.12
b=5
c=2
Substitute the values
Now substitute the values :
Now to find the height of altitude corresponding to side BC
So, formula of area of triangle
Since Area = 3.99 square units
So,
So,
Thus the altitude corresponding to the BC is of length 1.596 unit ≈ 1.6 units
Thus Option D is correct.