In programming, to declare a variable means to introduce a new variable in your code, specifying its name and, in some languages, its type. This is the step where you inform the compiler or interpreter that a variable exists, which allocates space in memory for that variable, but it does not necessarily assign a value to it.
So, the correct interpretation with respect to your options is:
To make space for a variable.
Assigning a value to a variable is typically done in a separate step known as initialization or assignment.