**Core Concept**
A twisting injury of the knee, particularly in a flexed position, is a common mechanism of injury that can lead to various types of knee injuries. This type of injury is often associated with damage to the structures that are most susceptible to stress and strain in a flexed position.

**Why the Correct Answer is Right**
When the knee is in a flexed position and subjected to a twisting force, the anterior cruciate ligament (ACL) is particularly vulnerable to injury. This is because the ACL is a key stabilizer of the knee joint, and its integrity is compromised when the knee is bent and twisted. The ACL's role in preventing excessive forward movement of the tibia relative to the femur makes it a critical structure that is often injured in this type of scenario. Additionally, the medial collateral ligament (MCL) can also be injured due to the valgus stress exerted on the knee.

**Why Each Wrong Option is Incorrect**
**Option A:** The posterior cruciate ligament (PCL) is less likely to be injured in a twisting injury of the knee in a flexed position. The PCL is more commonly injured in a direct blow to the front of the knee or a dashboard injury.
**Option B:** The menisci are indeed susceptible to injury in a twisting injury of the knee, but this is not the only option, and the question asks for the exception.
**Option C:** The medial collateral ligament (MCL) can be injured in a twisting injury of the knee, as mentioned earlier.
**Option D:** The lateral collateral ligament (LCL) is less likely to be injured in a twisting injury of the knee in a flexed position. The LCL is more commonly injured in a varus stress or a direct blow to the outside of the knee.

**Clinical Pearl / High-Yield Fact**
The "O'Donoghue's triad" is a classic association of injuries that can occur in a twisting injury of the knee, including the ACL, MCL, and medial meniscus.

**Correct Answer: D. Lateral collateral ligament.**