Which of the following is NOT a part of the runway environment for descent during landing?

The runway environment for descent during landing primarily consists of visual cues and aids that assist pilots in ensuring a safe approach and landing on the runway. Runway end identifier lights, visual glideslope indicators, and touchdown zone markings all fall within this category as they are directly involved in guiding the aircraft during its final approach.

Runway end identifier lights provide visual confirmation of the runway's location at night or in low-visibility conditions. The visual glideslope indicator helps pilots maintain the correct descent path, while touchdown zone markings indicate the area on the runway where the aircraft is expected to first contact the pavement.

In contrast, control tower notifications are not a physical part of the runway environment but rather represent communications that provide critical operational information to pilots. While they are essential for safe operations and may include instructions regarding approach and landing, they do not constitute a physical component of the runway environment itself, which is why this option is identified as not being part of the runway environment for descent during landing.