Which of the following is one of the significant features of Islamic art?

A. Portraits of Mohammed.
B.. life-size statues
C. Calligraphy.
D. Hieroglyphics.

C. Calligraphy.

To determine the answer, we need to consider the significant features of Islamic art and identify which one is listed among the options provided. Islamic art is known for its unique characteristics, which are influenced by Islamic teachings and cultural traditions. Let's evaluate each option:

A. Portraits of Mohammed: Islamic art generally avoids depicting human figures, especially religious figures such as the Prophet Mohammed. Representational images are discouraged in Islamic art.

B. Life-size statues: Islamic art tends to avoid creating three-dimensional statues or sculptures, especially depicting living beings. This aligns with the Islamic aversion to idolatry.

C. Calligraphy: Calligraphy is indeed one of the most significant features of Islamic art. The use of Arabic script is a prominent aspect, with calligraphic designs adorning various surfaces in Islamic architecture, manuscripts, textiles, and more.

D. Hieroglyphics: Hieroglyphics are not associated with Islamic art. Hieroglyphics refer to the ancient Egyptian writing system, which is distinct from Arabic calligraphy used in Islamic art.

Based on this analysis, the correct answer is C. Calligraphy, as it is a notable and distinctive feature of Islamic art.

The significant feature of Islamic art among the options provided is C. Calligraphy.