log in or log into?...

[SofiaRo]

Hello everyone,

I would really appreciate if you can tell what is the correct way to write (when you give written instructions for example):

a) log in to your account
b) login to your account
c) login your account
d) log in your account

If you can provide links where I can check it, please do so.
Thank you very much!
Looking forward to answering from you.

[Alan]

Standard (transitive) prepositional phrasal verb: log into, e.g.

Please log into your account.

Standard intransitive adverbial phrasal: log in, e.g.

I logged in at 7:00 a.m.