What is the difference between 'talk' and 'talk to'?

English as a Second Language English Teacher Explanations (ESL Tests)
1

Test No. [color=blue]incompl/elem-18 “Making an Appointment”, question 6

You arrange an appointment with another person because you want to … or see them.

(a) encounter
(b) greet
(c) meet
(d) talk

Test No. [color=blue]incompl/elem-18 “Making an Appointment”, answer 6

You arrange an appointment with another person because you want to meet or see them.

Correct answer: (c) meet
[size=200]_________________________[/size]

what is wrong when you use ‘talk’ in this sentence?

2

Talk requires a preposition: You can talk [color=blue]to or [color=blue]with a person.[YSaerTTEW443543]

TOEIC listening, photographs: The warehouse[YSaerTTEW443543]