Sentence 1: "security camera whose are part of a smart home system can send messages to the owners' phones"
The error is A. whose. "Whose" indicates possession and should refer to the cameras. However, the sentence structure is incorrect. We need a relative pronoun that connects the cameras to the fact that they are part of the system. The correct word is "that" or "which."
Corrected sentence: "Security cameras that/which are part of a smart home system can send messages to the owners' phones."
The other options are correct:
B. system: Correct noun in the phrase "smart home system."
C. send: Correct verb form.
D. to: Correct preposition.
Sentence 2: "they used to slling clothes and jewelry, and now they are rich from their business"
The error is A. slling. The correct word is "selling."
Corrected sentence: "They used to selling clothes and jewelry, and now they are rich from their business."
However, there is still an error in the sentence. The correct form after "used to" is the base form of the verb (infinitive without "to"). The sentence should be:
"They used to sell clothes and jewelry, and now they are rich from their business."
The other options are correct:
B. and: Correct conjunction.
C. are: Correct verb form.
D. from: Correct preposition.