Answer:
The options are not provided, however, nature in this context means;
The inherent features, qualities, or character of a thing or person that forms a part of his identity.
Step-by-step explanation:
In the contest of the sentence above, nature means a feature of a person that forms an integral part of his identity. We know this because before the word 'nature' was used, the features of the elderly man were described.
His physical features did not portray him as a person who had the inherent attribute of being playful. He was rather perceived as a person who had a serious disposition. Therefore, the best dictionary entry to describe this man is the one stated above.