Write a declaration for floating-point variable lastVal that’s to retain its value between calls to the function in which it’s defined.

The following are the variable declaration to this question:

static float lastVal;

Explanation:

In the question, it is already defined that a method is defined and inside the method a "lastVal" a float variable is declared that uses the static keyword, which means throughout the program its value can't be changed, and throughout the program, it's one copy is generated, and Inside the method, its declaration does not use such a variable, it only works locally.