awk extract rows with N columns

I have a tsv file with different column number

1 123 123 a b c
1 123 b c
1 345 345 a b c

I would like to extract only rows with 6 columns

1 123 123 a b c
1 345 345 a b c

How I can do that in bash (awk, sed or something else) ?

>Solution :

Using Awk

$ awk -F'\t' 'NF==6' file
1 123 123 a b c
1 345 345 a b c