Which of the following options declares a float variable?

The declaration of a float variable in most programming languages, including languages like C and Java, uses the keyword 'float' followed by the variable name. In this case, when you see "float age;", this correctly follows the syntax required to declare a variable named "age" of type float. The keyword 'float' specifies the data type, and the variable name comes afterward, separated by a space, which is the standard practice in defining variables.

This option clearly communicates that the variable will hold floating-point numbers, which are used for representing decimal values. The naming conventions of the variable also adhere to the rules of programming, where 'age' is a valid identifier.

The other options either utilize incorrect case or structure, as seen in the use of 'Float', which likely refers to something different or is not recognized as a valid type in many programming contexts. Similarly, 'flt' is not a keyword in most programming languages used to declare a float variable, and 'age: float;' does not conform to the typical syntax for variable declaration in languages like C or Java.