Final answer:
The most likely risk of taking benzodiazepines as a side effect is addiction.
Step-by-step explanation:
When taking benzodiazepines, a commonly prescribed anti-anxiety medication, the most likely risk Matilda may face as a side effect is D.) addiction. Although benzodiazepines are effective in reducing anxiety symptoms, they can also lead to tolerance and dependence. This means that over time, Matilda may require higher doses to achieve the same level of anxiety relief and may experience withdrawal symptoms if she stops taking the medication abruptly.