Final answer:
The question is not clear in its context as it refers to 'units from 499' in psychology, which does not correspond to any standard concept in physics; however, by drawing parallels to electric-field lines, the correct answer for a +20 nC charge, using the proportional relationship with a +5 nC charge, is 20 field lines (option d).
Step-by-step explanation:
The question posed pertains to the maximum number of units from the number 499 in the context of electric charges, where 'units' likely refers to the quantization of electric charge in terms of elementary charge units. In physics, the fundamental unit of electric charge is represented by the elementary charge (e), and all observable charges are integer multiples of this quantity, meaning electric charge is quantized. The question presented may contain a typographical error or an incomplete context, as the 'units from 499' is not a standard phrase in physics education regarding electric charge. However, if this is interpreted as pertaining to electric-field lines, which are an abstract representation used to visualize electric fields around charges, it can be addressed through understanding electric field lines conceptually.
Electrical charges are often visualized using electric-field lines, with the number of lines representing the magnitude of the charge. For instance, if five electric-field lines are associated with a +5 nC (nanocoulombs) charge, then to represent a +20 nC charge, the number of field lines would logically be four times greater (since 20 nC is four times 5 nC), indicating that there should be 20 field lines for a +20 nC charge (option d).
In summary, without additional context, the question about the maximum number of units from 499 does not directly relate to quantized electric charges or field lines. However, utilizing related principles of physics, we liken the concept to electric-field lines to illustrate the proportional relationship between the magnitude of charge and the number of field lines. Option d (20 units) would be correct when addressing the number of electric-field lines related to a +20 nC charge compared to a +5 nC charge.