The correct answer is C. URL Filtering primarily controls access to websites based on URLs, URL categories, and site classification. Administrators use it to allow business-relevant sites, block malicious or inappropriate categories, warn or inform users, and enforce acceptable-use policy. Option A is wrong because user credentials are handled through Identity Awareness, authentication infrastructure, or directory services, not URL Filtering. Option B is wrong because URL Filtering does not mean blocking all HTTP traffic; it applies selective policy based on site/category criteria. Option D is wrong because encryption of web traffic is provided by HTTPS/TLS and VPN technologies, not URL Filtering. URL Filtering becomes especially important because websites are often business-critical and risk-bearing at the same time; policy must distinguish between allowed sites, unacceptable categories, and dangerous destinations rather than treating all web traffic alike. Reference topics: URL Filtering, URL categories, website access control, Application and URL Filtering rules.