The blogger claims no originality of his question posted here.
Think of a field in some representation other than a diagram of field lines. For instance, suppose any point in a field is assigned a number to its field strength magnitude, but the direction of field strength of each point is not indicated. Now, could we deduce a rough picture of the (vector) E-field from these (scalar) numbers, provided that we know the distribution of these numbers and the position of charges?
In the figure, 
, 
and 
are charges of unknown charge quantities and sign. Each single-digit number at a point represents the magnitude of E-field strength at that point. For example, 
stands for 
, 
stands for zero E-field, i.e., a neutral point. By deducing from the figure, determine which of the following statements is/are correct.
(1) Charge quantity of is larger than that of either or .
(2) Charge quantity of equals charge quantity of .
(3) Charge is positive. Charge and charge are both negative.
A. (1) only
B. (2) only
C. (1) and (2) only
D. (1), (2), and (3)
Answer. D