IMO B
dense modifier, meaning issues,
A. When their eggs rejected by the host birds, certain cuckoos and cowbirds, in the name of parenting, resorting to bullying and destruction of host parents’ eggs, forcing many birds----> incorrect, no verb in the sentence
B. When their eggs are rejected by the host birds, certain cuckoos and cowbirds, in the name of parenting, resort to bullying and destruction of host parents’ eggs, forcing many birds---> correct, right placement of modifier, in the name of parenting
C. When their eggs are rejected by the host birds, certain cuckoos and cowbirds resort to bullying and destruction of host parents’ eggs, forcing many birds, in the name of parenting,---> incorrect, modifier error
D. In the name of parenting, certain cuckoos and cowbirds resort to bullying and destruction of host parents’ eggs, forcing many birds, when their eggs are rejected by the host birds,--> wrong, meaning change
E. In the name of parenting when host birds rejected their eggs, certain cuckoos and cowbirds resort to bullying and destruction of host parents’ eggs, forcing many birds---> incorrect, meaning change, modifier error