Which of the following statements are correct regarding dot product of vectors ?

1. Dot product is less than or equal to the product of magnitudes of two vectors.

2. When two vectors are perpendicular to each other, then their dot product is non -zero.

3. Dot product of two vectors is positive or negative depending whether the angle between the vectors is less than or greater than π/2

4. Dot product is equal to the product of one vector and the projection of the vector on the first one. Select the correct answer using the codes given below :

(a) 1, 2 and 3 only (b) **1, 3 and 4 only **(c) 1, 2 and 4 only (d) 2, 3 and 4 only