Question marks and dogs are the most challenging types of business units in the BCG matrix, requiring careful evaluation and strategic action to maximize their value and minimize their risks. When dealing with question marks, you need to decide whether to invest in them or not, using criteria such as market attractiveness, competitive advantage, strategic fit, and financial feasibility. If you choose to invest, you should pursue a growth strategy to increase their market share and turn them into stars. If not, you should harvest them for cash or divest them before they become dogs. For dogs, you need to decide whether to keep them or not, using criteria such as strategic importance, synergies, social responsibility, and exit barriers. If you choose to keep them, you should optimize them for efficiency and profitability or use them for other purposes such as cross-selling, innovation, or learning. If not, you should divest them or liquidate them as soon as possible. The BCG matrix is a useful tool for competitive analysis and strategic planning, but it is important to use it with caution and judgment, taking into account the limitations and assumptions of the model, the dynamics and complexity of the market, and the specific context and objectives of your business. By doing so, you can prioritize your business units and optimize your portfolio.