We have a dataframe 'customers' with a column "Birthdate' containing the birthdate of customers in the format $"$YYYY$-$ MM$-$DD$\text{'}.$ We want to calculate the age of each customer and create a new column 'Age'. We have today's year in a variable named 'year' as a numerical number. Which code is correct?

customers$(\text{'}$Age$\text{'})=$ pd$.$to$\_$datetime$($customers$[\text{'}$Birthdate$\text{'}].$dt year $-$ customer$[\text{'}$year$\text{'}]$max$()$

customers $[\text{'}$Age$\text{'}]=$ customers$[\text{'}$year$\text{'}]-$ pd$.$to$\_$datetime$($customers$[\text{'}$Birthdate$\text{'}]).$dt$.$year

customers $[\text{'}$Age$\text{'}]=$ customer.dt$.$year $-$ pd$.$to$\_$datetime$($customers $[\text{'}$Birthdate$\text{'}].$dt$.$year

customers $[\text{'}$Age$\text{'}]($pd$.$to datetime$($customers $[\text{'}$Birthdate$\text{'}]).$year