Study the DNA profiles obtained as a result of DNA fingerprinting of a child 'X' and three individuals 1, 2 and 3. Which one of the following options shows the possible parent of the child 'X' ?

The correct option is 1 and 3.

Step-by-Step Explanation:

1. Understanding the Principle of DNA Fingerprinting in Paternity/Parentage Testing:
A child inherits approximately 50% of their DNA from their biological mother and the other 50% from their biological father.
In a DNA profile (represented by horizontal bands on a gel electrophoresis template), this biological inheritance rule dictates that every single band present in the child's DNA profile must have a matching counterpart in either the maternal or paternal DNA profile. If a band in the child's profile does not match either parent, then those individuals cannot be the biological parents.

2. Analyzing the DNA Bands of Child 'X' from Top to Bottom:
By comparing the positions of the horizontal bands of Child 'X' against the three individuals, we can trace the source of each band:
• First (topmost) band of Child X: Aligns vertically with the topmost band of Individual 1.
• Second band of Child X: Aligns vertically with the second band from the top of Individual 3.
• Third band of Child X: Aligns vertically with the second band of Individual 1.
• Fourth band of Child X: Aligns vertically with the first band of the middle cluster of Individual 3.
• Fifth band of Child X (upper band of the lower-middle doublet): Aligns vertically with the bottom band of the middle cluster of Individual 3.
• Sixth band of Child X (lower band of the lower-middle doublet): Aligns vertically with the third band of Individual 1.
• Seventh band of Child X: Aligns vertically with the topmost band of the bottom cluster of Individual 3.
• Eighth (bottom-most) band of Child X: Aligns vertically with the bottom-most band of Individual 1.

3. Conclusion:
Since every single band in the DNA profile of Child 'X' can be fully accounted for by a matching band in either Individual 1 or Individual 3, these two individuals are the possible biological parents of the child.