Which words in this sentence make up the verb phrase?

The lowest layer of the atmosphere is named the troposphere.

a. is named

b. named the troposphere

c. layer is

d. of the atmosphere

1

The answer is B, because a phrase means that there is no active verb involved, and since there is 'named' in its passive form here, then it must be correct. A is a fragment of a sentence, C is the same, and D is a participial phrase.