The possessive form of the singular noun lifeguard is lifeguard's.
example: Always note the location of the lifeguard's station so you will be able to act quickly in an emergency.
Quantum is singular, not singular possessive. The singular possessive form is quantum's.
The singular possessive form of "test" is "test's".
The singular possessive pronouns are "my," "mine," "your," "yours," "his," "her," and "its."
The singular possessive of "ant" is "ant's" and the plural possessive is "ants'".
Museum is singular. Museum's is singular possessive. Museums is plural. Museums' is plural possessive.
The singular possessive form of "classmate" is "classmate's."
Taco's is the singular possessive.
The singular possessive of dish is dish's
The singular possessive is Martin's.
The singular possessive is fish's.
Grave's is the singular possessive.
Buzz's is the singular possessive.