An engineer is designing a Layer 3 campus network running EIGRP between the core, aggregation, and access layers. The access layer switches will be connected to the aggregation layer using Layer 3 copper connections. The engineer wants to improve convergence time for access layer switch failures. Which technique must the design include?
选项：

A: enabling BFD for EIGRP on the access layer uplinks
B: reducing the EIGRP Hello / Hold timer values
C: EIGRP summarization from core to aggregation layer
D: EIGRP summarization from access to aggregation layer