To solve this problem, we need to identify the symbol that represents mating between relatives in human pedigree analysis.$\newline$Let's analyze each option:$\newline \bullet$Option 1: A single line connecting a square (male) and a circle (female). This represents a normal mating.$\newline \bullet$Option 2: A double line connecting a square (male) and a circle (female). This represents consanguineous mating, or mating between relatives.$\newline \bullet$Option 3: A single line connecting a square and a circle with a vertical line leading to a filled square. This represents a mating with an affected offspring.$\newline \bullet$