Question

Present perfect
Mum and dad _____________________ each other since they were at university. *

A has known
B: had know
C; have known

Answer 1

Es la C

Mum and dad have know each other they were at University

Ya que el Has solo se utiliza cuando es he,she y it. El Have se utiliza para I, you, they y we

Espero que te sirva de algo esto :)