Final answer:
When British interest rates increase, German investors are likely to buy fewer dollar-denominated securities and the euro is expected to appreciate relative to the dollar, due to changes in investment attractiveness and resulting currency market dynamics.
Step-by-step explanation:
If British interest rates increase, German investors are likely to buy fewer dollar-denominated securities. This is because higher British interest rates make British assets more attractive, leading investors to prefer these over U.S. assets. Subsequently, the euro is likely to appreciate relative to the dollar. When U.S. assets become less desirable, as seen when U.S. interest rates are lower, there is a decrease in demand for dollars and an increase in supply of dollars in foreign currency markets, which typically results in the dollar depreciation compared to the euro. Applying this understanding to the scenario where British rates increase, we can infer that the euro would appreciate compared to the dollar due to similar investment dynamics.