refer to / denote / signify

[joseph0928]

What are the differences among refer to / denote / signify ?
1. The red line on the graph refers to the birth rate.
2. The red line on the graph denotes the birth rate.
3. The red line on the graph signifies the birth rate.
Are these three sentences all correct? What are the differences?
Thank you

 

[bhaisahab]

I'd probably use "indicates the birth rate".

 

[Barb_D]

Or simply "shows" as another option.

 

[tedmc]

How about : The red line on the graph is the birth rate?

 

[Matthew Wai]

How about 'The red line on the graph represents the birth rate'?

Not a teacher.