C

In Bohr's model of the hydrogen atom, the total energy of an electron in a particular orbit is given by the formula:
$$E_n = -\frac{13.6 \, \text{eV}}{n^2}$$
where \( n \) is the principal quantum number. The lowest orbit corresponds to \( n = 1 \). Therefore, substituting \( n = 1 \) into the formula gives:
$$E_1 = -\frac{13.6 \, \text{eV}}{1^2} = -13.6 \, \text{eV}$$
This indicates that the lowest orbit has a negative energy value, which means it is a bound state of the electron. Hence, the correct answer is negative energy.