The mean time period of second's pendulum is 2.00s and mean absolute error on the time period is 0.05s. To express maximum estimate of error, the time period should be written as

The correct option is (2.00 ± 0.05) s.

To express a physical quantity with its measurement error, we use the standard representation format:
Measured Value = (Mean Value ± Mean Absolute Error) Units

From the given problem, we have the following values:
Mean time period of the second's pendulum, $T=2.00\text{ s}$
Mean absolute error in the time period, $\Delta T=0.05\text{ s}$

Substituting these values into the standard format, the maximum estimate of error for the time period is written as:
$(T\pm \Delta T)\text{ s}=(2.00\pm 0.05)\text{ s}$