There will be total 3 three tables, because each MV needs separate table which contains PK + MVA.
Basic rule is to uniquely identify/ select any attribute when requested from database. If we put MVA into single table like
person_ID |
fav_colors |
age |
person_1 |
Red, Blue |
20 |
R2D2 |
Black |
22 |
In the above table, fav_colors are the multivalued attributes.The problem with doing it is that it is now difficult (but possible) to search the table for any particular fav_color that a person might have.
Multivalued attributes need a separate table so in my example we have only one Multivalued attribute(fav_colors).
Colors
person_ID |
fav_colors |
person_1 |
Red |
person_1 |
Blue |
R2D2 |
Black |
So, in your case it will be T1(dept_ID, A, B, C), T2(dept_ID, phone), T3(dept_ID, office)
Total 3 tables.