The table lists the measured rates for the reversible reaction X ⇌ Y.
Time (s) | Rate_forward (mol·L⁻¹·s⁻¹) | Rate_reverse (mol·L⁻¹·s⁻¹)
10 | 0.68 | 0.14
20 | 0.54 | 0.24
30 | 0.42 | 0.34
40 | 0.32 | 0.32
50 | 0.24 | 0.24
60 | 0.18 | 0.28
At which recorded time is the system first at equilibrium?
a) 60s
b) 30s
c) 40s
d) 50s