Final answer:
The net force on the -1 C charge being held is directed towards the larger charge of 1000 C, making statement 3 the correct choice. Statements 1, 2, and 4 are incorrect.
Step-by-step explanation:
When considering the forces on the charge of -1 C you are holding due to the adjacent charges of 0.001 C to your right and 1000 C to your left, we must apply Coulomb's Law. Coulomb's Law states that the force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. Thus, with a larger charge of 1000 C to the left and a smaller charge of 0.001 C to the right, both at equal distances, the net force on the -1 C charge will be directed towards the larger charge, which is the 1000 C charge to the left.
Statement 3 is correct: The net force on the charge you are holding is directed towards the charge of 1000 C. Statements 1, 2, and 4 are incorrect because the two forces from the charges are not equal and opposite, therefore, there will be a resultant force towards the larger charge, and not away from both charges or resulting in zero net force.