The correct answer is D .
Household penetration measures how many households bought the product, brand, category, or product group during the measured period. CMKG explains the panel-data formula as Total Number of Buying Households, or Penetration, multiplied by Spend per Buying Household equals Dollar Sales . It further explains that penetration relates to the number of households purchasing the product.
Option A describes purchase quantity or items per household, not penetration. Option B describes share of wallet or share of requirements-type spending allocation, not household penetration. Option C describes category dollar sales, not the breadth of the buyer base.
Household penetration is a reach measure. It tells whether the category is bought by many households or only by a narrow group of households.