为什么只执行一个IF语句？

Question

仅第一个IF语句运行，其余的则不执行。如果我单独运行它们，它们可以完美地工作，但是总的来说，它们不能工作。提前致谢。

import os.path

filename = input("please enter your file name: ") 

if os.path.isfile(filename):
    option = input("selec any of the below options \n Read a file: Press R \n Delete a file: Press D \n Append file: Press A \n") 
    if option == "r" or "R":
        readFile = open(filename, "r")
        print(readFile.read())
        readFile.close()

    elif option == "d" or "D":
       os.remove(filename)
       notesfile = open(filename, "w")
       notes1 = input("enter your new data: ")
       notesfile.write(str(notes1))
       notesfile.close() 

    elif option == "a" or "A":
       with open(filename, "a") as mylife:
           mylife1 = input("enter more data data: \n ")
           mylife.write(str(mylife1))
           mylife.close()
else:
    notesfile = open(filename, "w")
    notes1 = input("enter your data: ")
    notesfile.write(str(notes1))
    notesfile.close()