When the electrons of a chemical element change energy states, they release certain wavelengths of light that are unlique to that element. This means that the emission of light with a travelength of falls in the 620750 run range defining the red portion of the visible spectrum. __ the element caldium as the source of the Hight. (1) Mark for Revien Which choice completes the text so that it confirms to the conventions A having identified D Identifying C to Identify D Identifies

## Step 1
The sentence is discussing the emission of light from an element, specifically calcium. The sentence is incomplete and we need to choose the correct phrase to complete it. The sentence is in the present tense, so the verb that completes the sentence should also be in the present tense.

## Step 2
Looking at the options, we can eliminate 'having identified' and 'to identify' because they are not in the present tense. 'Identifying' is a present participle and does not fit the sentence structure.

## Step 3
The only option left is 'Identifies'. This verb is in the present tense and fits the sentence structure. It indicates that the element calcium is currently emitting light.