Its always a shared responsbility

Corporate governance is the system of rules, practices and processes by which a company is directed and controlled. Corporate governance, essentially involves balancing the interests of a company's many stakeholders, such as shareholders, management, customers, suppliers, financiers, government and the community.

Contracts: The primary tool of governance is the contract between a cloud provider and a cloud customer(this is true for public and private cloud). The contract is your only guarantee of any level of service or commitment-assuming there is no breach of contract, which tosses everything into a legal scenario. Contracts are the primary tool to extend governance into business partners and providers.
Ref: Security Guidance v4.0 Copyright2017, Cloud Security Alliance(used for educational purpose here)

Multifactor authentication is more secured than the rest because it has more than one aspect to authentication Multifactor authentication is composed of, at a minimum, two of the following aspects- something you know, something you are, or something you have. Something you know can be a password, passphrase, and so on. Something you have can be something like a number-generating transmit a number or fob, a smartphone capable of receiving text messages, or even a phone that can receive a call and then to the individual but that is only accessible from a very specific phone number.
Something you are is a biometric trait of yourself, as a living creature. This could be as unique and specific as your DNA fingerprint, or as cursorily general as a photograph.