Answer:
Es segura.
Explanation:
I´m going to explain this answer in two parts. First I will focus on the adjective: <em>segura</em> (safe) and then on the conjugation of the verb: <em>es</em> (is).
In Spanish <em>motocicleta</em> (motorcycle) is a singular feminine noun, so the adjective that qualifies it, in this case, <em>segura </em>must also be written in feminine. With this in mind, two options are ruled out: <em>es seguro</em> and <em>está seguro</em>, because both of them allude to masculine nouns (notice that they end in -o, unlike the feminine ones that end in -a).
Now let´s see the hardest part, why do you say <em>es segura</em> rather than <em>está segura</em>? Remember that the verb "to be" in Spanish has two meanings: <em>ser </em>and <em>estar</em>. <em>Ser</em> is used when you want to talk about a property (let's call it permanent) of an object or person. <em>Estar </em>refers only to (temporary) situations that may change at any time. In our case, <em>segura</em> is a property that is detected by the interlocutor as permanent: That motorcycle is not safe and, as it is by nature, he is afraid to ride it.