Which of the following is TRUE concerning natural language environment and formal language environment?

A. Formal language environment leads to learning one or more languages unconsciously, without much deliberate effort.
B. Natural language environment mostly results in explicit linguistic knowledge whereas formal language environment mostly results in implicit linguistic knowledge.
C. It is not possible to acquire a second language (L2) in a natural language environment.
D. It is possible for a person to develop knowledge of an L2 partly in a natural language environment and partly in a formal language environment.