All else equal, which of the following corporate changes should cause a firm's beta to rise? 1) An increase in the debt-to-equity ratio 2) An increase in the proportion of variable costs in the production process 3) An increase in the sensitivity of sales to changes in the business cycle O 1&2 only O 1.2. & 3 O 2 only O 1 & 3 only O 1 only O 3 only O 2 & 3 only