Book 1 Section 3.6 Q2

Looking at the Second Question on the Check for understanding:

I thought there were 2 “strong” beats in 4/4 meter - beats 1 and 3 with 3 being “less” strong than 1.

However, Looking at the question:
In the previous melody, how many notes are unstable and on strong beats?

I picked C - 3 notes

The official answer is: b: scale degree 2 over the vi chord and scale degree 3 over the V chord. Note that both of these unstable scale degrees (on strong beats) are resolved to a stable scale degree.

my question - Why isn’t scale degree 3 over the ii chord on beat 3 considered unstable on a strong beat?

What am I missing??

Thanks in adavnce!

– Other stuff for convenience –
Link: Hooktheory I
Hooktheory I

Quote from 3.2:
In the next example, we count out the beats of a four-beat measure. This so-called “four-beat feel” is part of a class of meters called “simple” meter. Try and count along with us, giving emphasis to the strong beats (1 and 3) in each measure.