Sarah was browsing an online shopping site when a program got downloaded onto her system without her knowledge. The next day she found that her search engine had been changed,and she received pop-up advertisements of the shopping site she had visited the previous day. The program on Sarah's system is ________.A) A cookieB) AdwareC) A payloadD) A Trojan horse

Adware is defined as the malicious software that induces virus in computer system so that it can display undesired online advertisements.These can appear on the system in the form of unclosable ad window or with pop-up configurations.They can also derive the user to the advertising website.

According to the situation mentioned in question,Sarah's system has adware program that got downloaded for displaying unwanted advertisements of the shopping site.

Other option are incorrect because Trojan horse virus can take the control over the complete system.Cookie is type of small file present in system.Payload is considered as the actual message part that needs to be transmitted .

Thus, the correct option is option(B).