Final answer:
The 'number of children couples decide to have' is a discrete variable, as it is a countable number and can only be represented by integers. The correct answer is b. Discrete variable.
Step-by-step explanation:
The variable representing the 'number of children future couples decide to have' would be a discrete variable. This is because the number of children is a result of counting and can only take on integer values such as 0, 1, 2, 3, and so on.
Discrete variables are quantifiable data that result from counting, whereas continuous variables would be those that result from measuring and can take on any value within a range, such as height or weight.
Hence, the 'number of children' in a family doesn't fit into the continuous, ordinal, or categorical variable types but is specifically a discrete variable.
A discrete variable is a variable that can only take on distinct values. In this case, the number of children a couple decides to have can only be whole numbers (e.g., 0, 1, 2, 3, etc.), rather than a continuous range of values.
For example, if a couple decides to have 2 children, they cannot have a fractional or continuous number of children.