Which line of code in the following Python program represents a conditional statement?

a$.$ line $2$: choice $=$ input$("$begin the exam: $")$

b$.$ line $5$: print$("$Notifying your proctor."$)$

c$.$ line $4$: print$("$You entered $"+$ choice$)$

d$.$ line $3$: if choice $==Y"$: