Out of 16 points in a plane, no three are in a straight line except 4 points which are collinear. The number of straight lines that can be formed by joining them is:

Correct option is C

Given:
Total number of points = 16
Among them, 4 points are collinear.
Formula used:
Number of straight lines formed by n points (no three collinear) = $$\frac{n(n-1)}{2}$$​​
Solution:
If no three points were collinear, total number of lines:
​$$= \frac{16 \times 15}{2}= 120$$​​
But 4 collinear points produce:
$$\frac{4 \times 3}{2} = 6$$​ lines
These 6 lines actually represent only 1 straight line.
So, extra lines counted = 6 − 1 = 5
Correct number of lines:
= 120 − 5
= 115
The correct answer is (c) 115.