The key schedule results in generating multiple keys from the one secret key. These multiple keys are used: a. in multiple sessions of communications one after the other. For example, if someone has 12 keys, they can use it for twelve video calls one after the other.
b. such that one of them is picked up at random at a time.
c. some as private keys, some as public keys.
d. for different rounds of encryption for the same plaintext to strengthen the cipher.

Option(d) is the correct answer to the given question .

Explanation:

There are various type of algorithm is used for the purpose of the key scheduling such as AES .in the AES algorithm we used same key for encryption and decryption of text .The  main objective of the AES algorithm it is used by Various round of the similar plain text encryption to reinforce the cipher text.

the benefits of raising bc’s minimum wage to $15 through a

series of pre-announced staged increases far outweigh the likely

costs. claims that such an increase will lead to massive job losses

in low-wage sectors of the economy are not credible.

• an increase to $15 would result in some job losses. however,

the likely impact is less than a 1 per cent reduction in the overall

provincial employment rate, and a 7.6 per cent reduction in the

employment rate for those currently making between $10.25

and $15 per hour.

• the large job loss impacts predicted by some opponents of

minimum wages misrepresent the existing economic research. in

reading and using that research, it is important to recognize that

estimates showing job loss effects of minimum wage increases

apply only to teenagers. estimated effects for young adult and

adult workers range from insignificant to non-existent.

• focusing on teenage workers plays up an inaccurate stereotype

about who earns very low wages in bc and leads to exaggerated

claims about job losses. only 26 per cent of those currently making

between $10.25 and $12 are teenagers, and only 5 per cent

of those making between $12 and $15 are teenagers.