Step 1: Identify the motion.
The object is tied to a string and released from a position where the string makes an angle
\[
30^\circ
\]
with the vertical.
At the instant of release, the speed of the object is zero. Therefore, centripetal acceleration is zero at that instant.
So, the acceleration is only due to the tangential component of gravity.
Step 2: Find the tangential acceleration.
For a pendulum released from angle \(\theta\), tangential acceleration is
\[
a_t=g\sin\theta
\]
Here,
\[
g=10\,\text{m/s}^2
\]
and
\[
\theta=30^\circ
\]
Therefore,
\[
a_t=10\sin30^\circ
\]
\[
a_t=10\times \frac{1}{2}
\]
\[
a_t=5\,\text{m/s}^2
\]
Step 3: Match with the closest option.
The calculated value is
\[
5\,\text{m/s}^2
\]
Among the given options, the closest value is
\[
4.9\,\text{m/s}^2
\]
Step 4: Final conclusion.
Hence, the acceleration when released is approximately
\[
\boxed{4.9\,\text{m/s}^2}
\]